Alternately, maybe it's the case that doing something bad to bring attention to another bad thing isn't okay just because the thing you're trying to bring attention to is worse.
I actually support the protests where they're throwing soup on paintings or whatever. Those paintings don't really matter, but some people sure think they do, and it's effective to get a dialog going. Libraries are a public good, one of the few we really have left. It's like ransacking a food bank to draw attention to starving people in Gaza; it's not helping the cause they ostensibly care about, but it is hurting others.