Got a source on the "stifling creativity" thing? I don't see anything about it in the abstract, and I don't particularly want to pay $36 to read the paper.
Interesting, thanks. That makes sense in retrospect and fits well with other research I'd heard of.
(tl;dr a wandering mind is good for creativity. Caffeine stimulates focus and inhibits mind wandering)
It's not quite a slam dunk though - the mind wandering is supposed to happen before the creative act. So I see no reason why going for a walk, then sitting down to write with a cup of coffee, should have any negative effects whatsoever.