Didn't you pay attention to what happened to Spirit? The restraining order against the pilot group was based on 500 pages of internet postings by about 10 people saying "fly the contract". Federal law has plenty of "features" implemented since 9/11 to permit them to pull your IP address from the forums, and therefore get your actual identity to be discovered during legal procedings.

If they can go after one person, they'll go after everyone, personally.

Don't be stupid, but then again it's probably too late, an archive of your post is probably already in the pile ready to go before a judge to prove a concerted and coordinated effort for illegal job action. That's exactly how it went down with Spirit, and the stack of forum posts that led to the TRO is public record so everyone can see how stupid "innocent" forum posts by just a handful of people can get used against everyone.