That is still a shitty prank.
I would not have called the cops, would have given them the pimp slap, however.
I fuckin hate vegan fanatics, but I admit similar " pranks " are an asshole thing in every possible way
I'd make them eat Dog shit meatballs with tomato sauce as a counterprank lol
Being either vegan or vegetarian is totally fine, but avoid trying to Force convert all the people around, just keep it for yourself and shut up