This kind of retribution is pretty normal from the companies I've worked it, it's clumsy that it ended up in writing here and a bit more vicious than usual with a child involved. Normally it's done offline in private conversations or simply as something that's understood between like minded managers with passing comments.

One manager I had was pretty candid about it, he said he couldn't find another job and was looking to retire so he was going to give me a bad performance review despite actually being the top performer so he wouldn't be affected. He was otherwise very apologetic that his hand was forced.