To steelman what I think the argument would be:

In a postmodern viewpoint (which has heavily influenced the development of queer theory and culture), most concepts are considered to be deeply intertwined with/defined by their social construction. Queerness, meaning same-sex/gender attraction and non-cisness, are defined as 'problems' in society because they subvert social norms. A postmodern/conceptual reading of queerness could state that the subversion is more integral to the concept of queerness than the actual details: For example, male crossdressing is seen as 'queerer' than female crossdressing because it's against the norm for men to wear women's clothing but not for women to wear men's clothing. What is considered queer enough to be 'queer' depends on social constructions. If queerness is defined by 'a lifestyle/way of being that is inherently transgressive of social norms, which are defined ipso facto by authorities (whomever they may be in a given culture)', then hackers' general stubbornness when it comes to doing things their way and refusing to bend to the easy/official way of doing things could be seen as 'queer'. Like a gay person who refuses a lavender marriage despite the social benefits it brings, a hacker may refuse conventional/well paying employment because they believe it violates who they are.

It's just, in my opinion, a stupid argument. I disagree on two key points:

1.) Not everything that is anti-authoritarian and contrary to the norm (and side-eyed for that reason) is 'queer'. All squares are rectangles, but not all rectangles are squares. The libertarians who want to abolish the age of consent are not 'queer'. The fundies who want there to be no educational oversight so they can break the 'norm' of having their kids learn history/science are not 'queer' even though they're both anti-authoritarian groups working against social norms. (Even most Christians send their children to school, and even most libertarians agree that having sex with 10 year olds is bad and should be illegal.) Hell, by that definition, TERFs would be queer inherently and I'm pretty sure OP wouldn't agree with that.

2.) Being homosexual/non-cis is not inherently against social norms and, in fact, the argument ignores that as the digital age allows for geographically distributed cultures, that the queer community itself propagates social norms for its members. (Many of which I disagree with, hence why I am so aware of them.) This is acknowledged with the term 'homonormativity' (e.g. to be a good gay, you have to be monogamous and married and act just like straight people, etc.). Breaking queer social norms carries the same penalties within the community as breaking greater society's social norms does - detransitioners are an interesting study group here.

Honestly, in my experience, the transgressive nature of queerness depends very much on a.) what type of queer you are [I'm picking up on the OP being trans-femme and they are generally seen as one of the more inherently transgressive types of queer, which likely influences their POV] and b.) what part of society you're in. I would actually consider my homosexuality to be one of the least transgressive aspects of my identity/behavior. My refusal to center romantic relationships/opting to operate in a long term household with a sibling is far more transgressive. My refusal to hide my disability and refusal to participate fully in/invest in my career because of it is far more transgressive. My refusal to care about my gender much and my choice to not pursue any kind of action to change my appearance to match my inner self (because I already have medical conditions and adding hormones/surgeries on top of that is a very unstable system + because as a visually impaired person I don't see why I should have to change how I look so the rest of you can feel more comfy with my gender presentation) is immensely transgressive in queer spaces because it suggests that gender/self validation is not exceptionally important to me/doesn't override other concerns. Etc.

I consider the main point of differentiation between queer culture and hacker culture to be about validation and interaction with broader society. Queer culture cares what society thinks: people in it want validation and acceptance and in fact, a lot of queer spaces now primarily function as validation/hugbox chambers, and I see a distressing lack of self-actualization and agency. Hackers overcorrect in the other direction: they're actively hostile to (at worst) or indifferent to (at best) the concerns of greater society. A hacker is generally expected to have a decent sense of self-worth/self-esteem, and going into hacking spaces and being asked to validate someone wouldn't be taken well. (It's really common to see 'am I really queer/trans enough? Am I really a lesbian? Please call me girl/boy things to help me experience gender euphoria' etc. in queer spaces, whereas 'I ran a script on someone's computer, please tell me I'm a 1337 haxxor so I don't get depressed' in hacker spaces would go over like a lead balloon). I'm not really claiming one is better than the other: I prefer hacker spaces ironically because I'm a fairly masculine woman and I despise being used as a validation/vent/therapy machine, but it also has its issues. Like since you're expected to have a rock solid sense of self, people slinging gross insults at you based on parts of your identity is something you're supposed to shake off or you're the sensitive one. I'm totally chill at being called a moron/flamed for stupid questions and suggestions, but as someone who was once a teenaged lesbian, things like the corrective rape threats were over the line.

Unfortunately, it's unlikely we'll know exactly what they meant. The comment was constructed like a Tweet or Tumblr post meant to rally the troops/get 'yaaas queen slay' type responses. An actual desire to discuss would have included things like their reasoning, where they got their information, and/or indications of how sure they were about different parts. And they would have tailored their response to their audience. (I certainly write differently here than I do elsewhere - I would not call myself a 'homosexual female' elsewhere, but HN has a strong preference for technically descriptive terms and doesn't generally ascribe as many inferences to them, so I used those words here.) Instead, it was just blanket 'X is true and I will not elaborate I'm so smrt' type posting.

*edited 'associate' to 'ascribe' because MS aphasia is a bitch and I mix up words now