The dog didn't seem to have a vest on, and also I noticed the dog was laying down on his side all sprawled out. I don't know if this is the case, but guide dogs that are in "work mode" won't lay like that, right? They will sit at attention, but he was all sprawled out.
Also I've dropped plenty of drinks before, they don't splash like that. I've also been known to passive aggressively "accidentally" drop things like that.
that said, yes, no one has the right to punch someone like that. But was the punch caught on tape?