I think it would be okay to do it to any bike, I suppose, especially rare and costly ones. It's the owner's bike to use as he pleases, yes? Classic capitalist theory would suggest that the owner would be restrained from wrecking a bike because doing so would reduce his value. Unless the owner is an ignoramus, of course, in which too bad for the world's supply of quality older bikes.
I guess I'm turning into a curmudgeon, but it just strikes me as odd that there are people who would pay extra for a pre-vandalized bike. "When I was a lad, we used to have to vandalize our own bikes, by thunder!"
JV