Full disclosure: I've known jg since 1986. I have no insight into the Apple goings on, but the story that "he's the guy that made Siri suck" sounds very very unlikely to me.
Yeah, not attributing it to him, just his lack of being able to do anything with it. Could have been Apple Politics. Could have been a number of things.
Still. Idle hands, he should get back on that horse if he can. Go do more stuff.
He's not the guy who made it awesome, that much is known.