While it is certainly informal to say "guys," I have heard both men and women use it in a definitely gender-neutral sense for my entire life, including in workplaces, and informality is not impolite in an informal setting like an IRC channel. I wasn't sure if I was crazy here so I asked a couple of women I know and they were as surprised as I was. By contrast, nobody uses the word "gals" - it sounds incredibly awkward and lame. Perhaps the use of the word "guys" is regional, like "y'all" (sadly, it seems like English does not have any universally established pronoun for this). It's sad that you are proud of treating people who are new to Rust by permanently excluding people and labeling them as assholes for using idioms which are considered perfectly courteous and gender-neutral in many places. Given that, banning people just for using the word "guys" smacks of finding excuses to harass and ban people more than offering a welcoming community. If this is "what usually happens in IRC" then that might be a clue that there are dialect differences you aren't recognizing?

Insofar as you are representing the Rust community via HN, you've given an overwhelming impression that the Rust community is an unpleasant place where "outsiders" are totally unwelcome. As someone who considered adopting Rust prior to reading your post, that's a problem because with such an immature language I would eventually have to interact with that community and then I would apparently have to deal with people randomly nitpicking which dialect of English I learned and calling me an asshole. No thanks, life is too short.