Thing is I didn't overreact. The response I started to type up was more joking and exactly, "Hey, don't do this again." And in response to his point about banning for posts made earlier in OOT, this was exactly what I was going to say:
No
Then I stopped and thought about it. From my viewpoint he knew he wasn't supposed to do that and did anyway. Other mods encouraging it I don't understand. The rules are there for everyone. They were put in place quite a while ago, and I'm not making an example out of anyone. I like Yeti. This sucks. But the rule has to be enforced if it's there, and I couldn't think of a reason this was ok.
It's not surprising to me that some don't like this, but I'm not going to understand the following as reasoning for bans if some of the same thinking isn't applied here. I hear all the time that if a user can't read the stickies that's their problem and we should have no sympathy for them etc, etc. The mod sticky is very short.