Not to rehash, but I finally decided to go into the demand letter to see what these fools think they have on Iowa.
The accusations are basically the same ones that our friend Robert T. Green publicized over the summer and I won't rehash those here.
The theories of liability are basically Title VI and 42 USC 1981.
Title VI says that no institution that takes federal money can discriminate against enrolled individuals on the basis of race while they are enrolled. The hurdle this bunch has to clear is the statute of limitations - any lawsuit has to be filed within two years of the offending conduct or get tossed out of court. The most recent transferee out is Aaron Mends, who left in December of 2018. Everyone else left the program in 2014-17, which means their SoLs are lapsed. There are many clever lawyers who try to argue that various and sundry acts can toll the statute, but those clever lawyers always get shut down by federal judges. (Mends still has two months on his, but he has to prove that the discrimination he experienced basically happened between October of 2018 and December of 2018. At best, his claim is, um, circumscribed.)
42 USC 1981 says that you can't discriminate on the basis of race in the making of contracts. The argument, as best as I can tell, is that the alleged discriminatory acts qualify as some kind of employment discrimination against the individuals. The statute of limitations for 1981 is 4 years, so in addition to Mends we also have Joly, Parker, and Wadley with non-time-barred claims. The others would be time barred. Even clearing that hurdle, though, you have to successfully argue that the ex-players were employees of the University, which is a questionable legal argument (and one argued unsuccessfully by Northwestern athletes some time back). (Then again, this particular attorney is apparently suing various and sundry entities for slavery reparations, which, well, speaks for itself.)
TL;dr, they're up a creek without a paddle and hoping to catch a fish. Good luck to them.