What I don't get is, if you're really gonna do something like that, why would you just throw the paint on randomly? He should have at least written a message.
At least it's better than the dingleberries who vandalized a horse statue to turn it into a MLP.
Wait, seriously!?
I just looked it up, and yes, it happened. It seems to be that someone painted a bronze horse statue in Russia in the colors of Rainbow Dash recently. Gonna take a guess and say it has something to due with the Russian government's homophobia. Naturally the article I found had comments either say "fuck bronies" as hard as possible, or alternatively, "fucking awesome!" One site was also giving bronies shit for giving guns pony themed paint jobs.
On topic: Why not do something funny like leave two giant boulders in a massive burlap sack at the base of the Washington Monument?