This is from his twitter:

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. :-)

I'm pretty sure they'd PAY him to talk at Quakecon. Although it's not a big money event, so they'd probably just ask really nicely. :)

I am pretty sure there is 0 chance that I would pay attention to quakecon if not for Carmack's talks.

Amen. That is the biggest thing I'll miss as a result of him stepping down. They'd really be screwing up their conference by taking him off the docket.

Yup - I read it as something akin to "my husband, who has become interested in focusing on things other than his family, has separated from me... but his children are incredibly smart, and we'll do fine without him".

Could also just be careless writing by someone not trained in the art of writing statements that will be dissected by the media and public.

It doesn't read like a statement that has been carefully crafted by a team of copywriters, PR flaks and corporate lawyers.

I think the author is perhaps just worried that the perception will be that there's something wrong with iD.

I don't think it's flippant at all.

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.