I don't think they are afraid of the new federation. I think they are afraid of Lee letting people know where the bodies are buried. With all these people coming out against him, they are making themselves look just as guilty because they knew what was going on and did nothing. In fact, they continued to promote shows with him and be affiliated with him and he was supposed to be the worst guy ever. Right. He wasn't the only one doing shady stuff and if they piss him off enough I bet it's going to start coming out.
That's why they got all their superstars to come out singing for the IFBB. They are afraid of the shitstorm that will occur should LEe decide to sing.