Liking a band (even to the point of purchasing and subsequentially wearing a shirt in public) does not neccesitate subscribing to the political (or other) opinions of the bandmembers.
I'm certain that plenty of the members of bands for which I have a t-shirt have/had opinons I disagree with. I don't care and finding something like that out wouldn't disallusion me.
Furthermore I have never gotten interested in a band from finding out about the political stances shared (or not) by the bandmembers.
I can't imagine Johnny's statements at the R'n'R HOF induction (or eslewhere) caused any significant percentage of Republicans/President Bush supporters to go out and buy Ramones shirts. Similarly I can't imagine any signficant percentage Democrats/President Bush detractors swore off the Ramones after said remarks.
As for the other comment, you can always rely on The Onion to cover such news tactfully (see In the News.)