Perhaps it was only one stupid comment. He saw the cat with the bills and remembered the cat's photo site. It's not a very relevant comment and it breaks the "no cat's photos" rule. But it's not extremely offensive or plain spam or tinfoil hat talk, and the older comments from the user look good. So IMHO I think it deserves only a few downvotes (maybe 0 or -1?), banning the user for this is too much.