Earlier quoted context omitted.
or the bot is taking advantage of holes in the existing spam filter that haven't been exploited before
Obviously you can't filter for every possibility in advance, but with a hands-on moderator and some regex it should be super-easy to throttle this. And as more than one person has pointed out, just shutting down new account creation/posting for 24 hours would be equally effective. I'm perplexed at how a mature site full owned and catering to network technologists is vulnerable to such a laughably crude attack.
You're right that it's laughably crude though. Says a lot about things that this hasn't happened until now.