I've been searching the interweb for similar cases to see just how plausible this "revocation" thing is. It seems like the highest-profile analogue, which actually made it into real-life courts, is that of Patrick McHardy.
https://www.zdnet.com/article/linux-beats-internal-legal-threat/
http://laforge.gnumonks.org/blog/20180307-mchardy-gpl/
https://www.zdnet.com/article/what-happens-if-you-try-to-take-your-code-out-of-linux/
https://www.synopsys.com/blogs/software-security/gplv2-right-to-cure/
https://gplcc.github.io/gplcc/
It seems like at least in Germany, courts were unsympathetic to these claims, but not entirely dismissive. The defendants admitted outright that the GPL had been violated, but McHardy backed down rather than going full autist on proving his "authorship" in court, under cross-examination, for each diff. Probably doesn't make sense when you're paying a lawyer by the minute. But the argument itself was never rejected - it seems like it would still be possible to make a successful claim of some sort if you were willing and able to prove it.
The general consensus seems to be that you can't revoke your license
just because you're buttmad on the internet (I found a few cases like this that amounted to nothing), but as soon as you find one comma out of place that
genuinely breaks GPL compliance, it's off to the races. It seems like there's no real solution to this problem - abusive enforcement of GPLv2 (and derivatives like the Mozilla Public License) apparently can't be stopped unless you get contributors to sign away their rights (
as the FSF does, for example) when committing. The only countermeasures are social: encouraging developers to sign on to things like
GPLCC, using newer licenses like GPLv3 that are less abusable, and ostracizing any big-name developer who tries to pull stunts like this.
Point is: Windows XP is for lolcows, but license abuse is apparently a real thing. If you're working on code that might reach public eyes, read the fine print and understand it.
Incidentally, I think I once saw some Wikipedia lolcows try something similar once - Wikipedia pages used to be licensed under the GFDL which had similar termination provisions, before they transitioned (so to speak) to Creative Commons. I wonder how that turned out.