Good for Bjork. It may not be much, but you can be damn sure that if there were any pro-Tibetan sympathisers in the audience they appreciated it. (I'm guessing Bjork's audience was probably largely the moneyed middle-class and I'm guessing they probably have better access to the limited information available about such things.)

Plus I don't see how a foreign artist those two words endangers activists' lives any more than they are already.

I increasingly believe that there's much more force in a visiting dignitary (as it were) embarassing the authorities in situ than a wholesale cultural boycott, in which no one plays there in the first place.