zahavasdad: There are different halachas whether the property being damaged/destroyed in a yid or a nochri’s. And in various circumstances (such as this case) it is not only permissible, but it is obligatory, in either case.
apy: If we could do it without being hurt, we most certainly would. But that is a different issue in any event. Inadvertently seeing an avoda zora is not an aveira. Inadvertently seeing this filth that was destroyed, is an aveira. An hence that object of sin must be removed.