It's not against the rules to use the words, it's just that when you write a psa for the forum you need to keep your tone neutral and unemotional as it's super easy to slip into being angry, I know I've done it before.  If you're ever in doubt you can go into the Service Review forum and they have the rules/ code of conduct for posting psas there.  It's helped me a lot when I've needed to write PSAs and reminded me to always look over my posts.