The issue is not with the NFL owners. It is with CNN and other media outlets who should be sued for libel if they cannot offer proof of Limbaugh's alleged comments.
Well, who is believing those stories?
If the NFL owners manned up and had the accusations vetted, then manned up again and say that “CNN and other media outlets” are full of hogwash on this issue and they are glad to have Rush Limbaugh on board, they would get a lot of cheers from the conservative half of America.
I wonder, though, if this is only an excuse and the existing owners are afraid that Rush might get a bit Dutch Uncle about shenanigans by the team players.