Also … I don’t think the NFL has an antitrust exemption from Congress. If they did, then the USFL would have had no legal basis to sue the NFL back in the 1980s.
For what it’s worth, the USFL actually won that lawsuit — but were awarded only $1 in damages because they couldn’t prove that the NFL’s monopoly harmed them in any way.
Here’s an article about the NFL’s anti-trust exemption.