Well honestly, that part about Github was a bit of a joke grounded in some real-world experiences. Mainly I was just referring to people who act mighty about something that is in essence, nothing. Further, I am referring to people who obviously are struggling over basics, but are not humble enough to recognize it. Amazingly, people love to brag about things they are actually not skilled in at all.

As for public facing programming-related artifacts and sites, I don't think it's a good idea in general to judge people on things like Stackoverflow, Github, etc. It's not that I don't at all and not that my colleagues don't, but rather we place appropriate weight. Mainly when we asks for things like this, we just want to see what your writing and code looks like to get an idea. If a candidate said to me, I don't have a Github account or I have better code I can send to you, then that's fine. There are so many arguments why judging people this way is bad that I would end up writing a book in reply.

This is why sometimes we'll do a coding test regardless because then we can at least have greater confidence that the person actually wrote the code we are looking at and that they are capable of executing the type work we are interested in doing. Even for coding tests, we mainly put weight on the explanation the candidate gives rather than the code. You learn a lot about how someone understands problem solving by asking them to explain their code and walk you through it. Moreover, it helps weed out the cheaters, pretenders, and liars, of which there are many.

Regarding your case, I would never really penalize someone that harshly based on their commit history, at least in isolation. As you explained, there are many factors at work. If a candidate explained why there were so many commits and 3 months ago, he did x and then now he's doing y, I wouldn't care. I would actually just look at the explanation itself, rather than the commits.

Be wary of any employer that cares too much about your Github. Although one should be humble in interviews, you also to a small degree are seeing if the company and people are a good fit for you. If the interviewer is placing too much stress on things you feel are irrelevant, it may or may not be indicative of other future problems with them. I have noticed for instance that people that I have co-interviewed someone with sometimes become very antagonistic when they feel threatened by the person they are interviewing. That is, their ego gets in the way of doing a constructive interview.

If I had to pick specific things I look at when viewing anyone's work including Github:

1. Clean code with a consistent style. This is rather subjective, but I think that most of us develop a feeling for the things we want to see. A good developer searching for other good developers should recognize that good is not simply coding very similar to yourself, but rather that the code has easily identifiable merits, even if you disagree on some choices. Simple things like namespaces and following the standards of the language are easily identifiable and hardly debatable.

2. Understands the material. In the case of Github and your commits, part of that might be understanding how to use git. Things like rebase vs. merge come to mind, cleaning commit history and branches, and so on. We all make mistakes and do stupid things like use git to move things between machines to get something done fast. It's fine, just keep things tidy and use the tool properly most of the time (preferably all the time obviously). If it's a programming language, don't write Lisp like C++, don't write JavaScript like Java, and so on.

3. Recognizable that it is actually the person's work and not plagiarism. Bigger problem than you may think.

4. Obvious that something of value has been created. I've seen a lot of node.js projects linked to me by candidates that are in essence doing nothing but wrapping something else, then outputting it to a pretty UI that came from someone else, i.e. Bootstrap. A lot of this can be fine, but there better be a point to the project and the description given by the candidate should match reality. If it doesn't, it just feels like bs or a lie. It's OK to use tools like Bootstrap, but just don't take credit for those parts as if you did it all yourself, from scratch in assembly or something.

5. Good behavior. This can mean a lot of things. For example, how does the candidate interact with issue submitters? Is the documentation broken? Do they seem to post a lot of crazy, false, ridiculous stuff everywhere (your language sucks type stuff, sweeping false generalizations, etc).