Of course. I remember reading transcripts of Cristopher Poole cooperating in court during a trial. He used to straight up tell users he would fully cooperate with authorities if required. Nobody there is in the business of going to jail.

You're anonymous to other users. Unless you're behind seven proxies, connecting your posts to your real identity is as simple as correlating 4chan logs with ISP logs. Usually that requires court orders so it tends to happen in response to real offenses. Insulting each other with slurs isn't enough for a court order so it's fine. Chances are the NSA knows all your posts regardless.