I'm surprised you guys are bothered by this. The registrant isn't going to be able to enforce the trademark, so why not save your energy and ignore him?
You really don't think that if one were established as the trademark holder on Bitcoin they couldn't cause greif for a domesticly run business that was buying, selling or trading Bitcoin?
I don't think grief is necessary. If your (U.S.) business gets a nastygram from their lawyer, just switch to the term "Bit Coin" for the time being (since the ordinary words are not trademarked). Then their lawyer sends a nastygram to the next Bitcoin business, and the next Bitcoin business, and so on. Eventually they run out of money from paying lawyers and abandon their trademark, and everyone resumes using "Bitcoin".
Spending time and energy worrying about this is pointless.
and what do you propose for businesses that have "bitcoin" in their registered name? or their official copy? or slogans? just go change it? good thinking /sarcasm