It's not an ad hominem at all. She made claims that are, for random internet speculators, fundamentally unverifiable. Indeed, her claims simply cannot be proven either way via discussion. It's little more than "he-said-she-said." In situations like this, you have nothing to go on but perceived trustworthiness. Prior events that might damage trustworthiness are not irrelevant.

>Fact of the matter is, it's too early to say whether she was wrong or not

Obviously, but you can speculate and weigh the possibilities.

We have a disgruntled employee (who is no longer with the company) writing a piece attacking her former company and some people working there. That brings a lot of doubt over the validity of her claims already.

Add to that the hilarious debacle this employee created a few months ago over a rug that so brazenly included the terrorizing, offensive, gross word 'meritocracy' on it.

If someone thinks 'meritocracy' is sexist, might they also think a totally ordinary workplace happening is sexist?

My bet is on her claims of sexism being a waste of time (you do know that you can speculate on something without being totally sure, right?).

For the rug thing: http://www.google.com/search?q=meritocracy+github+rug

Just so you know, the word "meritocracy", is in fact a parody, but because bitter irony has led to its being seriously adopted by some people recently, there is general consensus among people actually studying sociology (rather than some dudes with opinions) that "meritocracy" really is sexist as well as racist. If you care to learn something new, you can look it up and understand why, rather than dismiss something based on ignorance.