It should be noted that one of the strengths of the Linux community (and others, of course) has been to integrate people with less than perfect social skills or lacking in empathy, bordering on asperger or autism sometimes. (Yours truly is affected and thus allowed to comment ;-)
These people sometimes bring exceptional technical skills to the community (alas, yours truly is not affected here), which they would have not been able to leverage in a more typical day-to-day office setting with pair-programming, lots of communication, and so on.
That is by no means an excuse for being rude, and sometimes apparently not even trying to overcome the issue (but apparently rejoicing in it), as often evident on LKML - but I dare say it is advisable to find ways how to integrate them, instead of forking away from them.
Personally, having been on some projects affected by such people, I think they make wonderful to exceptional engineers. It becomes difficult when they remain project leaders of a growing community.
Of course, it's not always possible for them to accept switching roles (control issues anyone?), but it should at least be considered by everyone. And if so, proposed in a face saving way for all involved - the comments on the terse (and arguably rude) bugzilla responses were just equally rude and juvenile, and certainly unlikely to yield a positive response.
If even that fails, sure, fork - or build up a trailing repository which pulls from the former upstream frequently as done here. Maybe even do that in parallel, to demonstrate seriousness (and ability). But don't forget the other side.
(And yes, before someone reminds me about what we did with Linux-HA, yes, sometimes, after all this has failed, running for your life is the only way to remain sane.)