> She never presents an argument why what he said was problematic

Okay, then I will.

Stallman states incorrectly that "The word “assaulting” presumes that he applied force or violence, in some unspecified way, but the article itself says no such thing. Only that they had sex."

That is incorrect because "sexual assault", according to US law, means "any nonconsensual sexual act proscribed by Federal, tribal, or State law, including when the victim lacks capacity to consent." - https://www.law.cornell.edu/uscode/text/34/12291#a_27 (34 U.S. Code § 12291 (29)).

While the military has a different set of laws, I'll point to https://www.law.cornell.edu/uscode/text/10/920 as an example, because it's clear and easy to find:

(b)Sexual Assault.—Any person subject to this chapter who—
(1) commits a sexual act upon another person by—
(A) threatening or placing that other person in fear;
(B) making a fraudulent representation that the sexual
act serves a professional purpose; or
(C) inducing a belief by any artifice, pretense, or
concealment that the person is another person

You can see that "force or violence" is not a requirement for sexual assault.

Similarly (again, this is from military law, but similar principles apply to civilians)

(2) commits a sexual act upon another person—
(A) without the consent of the other person; or
(B) when the person knows or reasonably should
know that the other person is asleep, unconscious,
or otherwise unaware that the sexual act is occurring;

It's still sexual assault even if no force or violence is needed because the other person is unconscious.

In all of these, the key aspect is "consent", or rather, the lack of consent.

Many of Selam G.'s arguments are based on the legal concept of consent. For examples:

> then he says that an enslaved child could, somehow, be “entirely willing”.

The law is that an enslaved child cannot consent to sex in this way, so cannot be regarded as being "entirely willing."

(As another example, an 11 year old student may be "entirely willing" to have sex with his/her 35 year old teacher - it's still illegal as the presumption is that proper consent cannot exist at that age and power relationship.)

Stallman attempts to justify this as: “I think it is morally absurd to define “rape” in a way that depends on minor details such as which country it was in or whether the victim was 18 years old or 17.”

As the topic is an accusation of sexual assault, which is a legal definition, and which seems to be correctly applied for this case, it is irrelevant to bring up a personal view that the law is wrong.

More problematic, we all know that hard age numbers like this have problems. What magic is there that I can buy beer in Canada at 18 but cross the border it's a problem?

But age is an attempt to make the law clear. If 17 is fine, why not 16? 13? 8? 2? Make it too young, and there cannot be consent.

Since Stallman doesn't seem to accept that concept of consent, can we assume that if Prof. X of MIT had sex with an "entirely willing" 5 year old, it would have been okay according to his morals?

I hope not! But the problematic part is Stallman never presents a valid argument why sexual assault is the wrong term, and the best reading I can make of his views is that he doesn't understand consent. Which is indeed problematic.

As an example, if someone notifies him that FSF organizer Foo sexually assaulted Bar by having sex with Bar while Bar was drunk and asleep, and who did not previously give consent, would Stallman respond that that wasn't assault, and not address the actual issue?