There are posts in this thread that would subject the poster to a reasonable risk of losing a libel suit, assuming it was worth it to a plaintiff to trace the posts to an actual human being with a name. Which it almost certainly isn't. But the thought that a poster could convince a jury that they have a reasonable basis for their belief that a felony was committed by watching players play poorly is absurd.
But, since you're an expert in everything, I'm sure you think you know more about libel and slander law than I or anyone else does as well. After all, I'm sure you once stayed at a Holiday Inn Express.
By your logic, claiming professional wrestling is staged would be slanderous to the wrestlers since likely none of us have first hand proof that professional wrestling is staged. Obviously, that is not the standard, and you know that.
Major conference basketball players that have been on television dozens of times are public figures by any definition, and people are opining on their actions in the arena in which they became public figures. The bar for proving libel or slander is REALLY high in that situation. Someone would have to say "I know Person X fixed a game for money" when they KNEW it was not true, have no evidence to support such an accusation, represented themselves as being a credible source for information, AND did so deliberately with the purpose of hurting the reputation of the person accused, for someone to be liable for libel or slander in that situation. Some fans on a message board saying that a game looks suspicious, and providing over a dozen examples of why the game looks suspicious, is pretty far away from an action that would make someone civilly liable.
On the other hand, any lawyer even threatening a frivolous slander or libel lawsuit with the purpose of intimidating someone into shutting up about misconduct could risk disbarment and potential criminal conspiracy charges if it was later shown that the lawyer knew or should have known that their threatening actions were in furtherance of criminal activity. In other words, the legal standard of behavior for a lawyer is much higher than it is for a regular citizen.
And I didn't stay in a Holiday Inn last night, but I have dealt with bullying lawyers over the years who think throwing around some legal jargon makes them wizards or something.
p.s. Are you one of those lawyers that threatens lawsuits if someone posts a review on TripAdvisor that their chicken was overcooked or the lettuce was soggy? A friend of a friend is a manager at a chain restaurant, and they are ready to go scorched earth on their customers. Should I send them your way?