"John Carmack, who has become interested in focusing on things other than game development at id, has resigned from the studio,""
It does sound kind of testy/flippant to me. But it could be out of context.
I wanted to remain a technical adviser for Id, but it just didn't work out. Probably for the best, as the divided focus was challenging.
And then:
If they don't want me to talk on stage at Quakecon next year, we'll just have to fill up the lobby like the old days. :-)
It doesn't read like a statement that has been carefully crafted by a team of copywriters, PR flaks and corporate lawyers.
It comes across as very succinct and matter-of-fact to me. His focus is elsewhere, so it's not a great fit for him to work there anymore, even if he is the founder.