It does look a bit like a cackhanded attempt at 'Bleurd', in a Hammer House of Horror style. Maybe some thoughtless DIY gore filmaker?

If this stone painting behaviour gets much more prevalent, there's going to be sufficient cause for to someone to develop a reproducible method of paint removal. The pic makes it look like the paint has sunk into the stone, which sort of seems even worse than the recent case of gloss yellow elsewhere :(

I reckon that you could stop this kind of thing with a sign, but it would probably need to be applied forcibly to the painter's cranium. Perhaps repeatedly.