Okay, you’re right!. As private citizens we don’t have to allow others free speech.
But vandalizing people’s private property, as far as I’m aware, is still against the law.
For it to be defined as vandalism, it has to be a lawful commercial expression, in compliance with local ordnances. Let's exclude what these banners were, and instead look at the local ordnances. Displaying of a banner over a commercial enterprise requires a permit in Reno, Nevada. I'm sure a check of the proper licensing bureau will show that no banner permits were filed for the display in question. Whereas an American flag would traditionally be ignored by any code enforcement officers, it is still not a legally proper display at a business without the requisite permit.
Removal of an illegal display would only create the liability of actual damages. IE: If I hang a banner in front of my business that drapes across a handicapped parking stall, and a van busted it down pulling into the space, my actual 'loss' would entail the string that held it up.
So the Vet in question had a liability of five bucks, the actual 'loss' of the flag, the owner would have to demonstrate that they received zero compensation from that loss (an impossible thing to prove, but I guarantee that there are those in Reno right now who are going to his business because of the publicity of the news story), so his actual 'losses' are zero.
Now, if you were talking about someone's home where this occurred, my stance (and I'm pretty sure most everyone elses' on this board) would be completely different.