Yep, the NCAA has an impressive series of court wins behind them. Maurice Clarett and the Colorodo snowboarder come to mind. I thought both of those players had good cases and they both lost. But in each of those the NCAA had proof of benefits to point to as a reason for declaring the student was not an amateur. So far, they don't here. I can't think of a case where the NCAA went to court and won based solely on suspicion. Maybe there is one though.
Don't make the mistake of forgetting that the NCAA most likely only goes to court when it thinks it will win. Even if it loses, most likely it will be narrowly, in a way that will not affect other cases or the way they do business. But one bad case can change everything. They are not worried about a financial judgement in Sidney's favor, they have deep pockets. They would only worry about a case that might derail the gravy train in some way.
I agree that financial records are causally related. I think the house rental is the one thing that puts this on the NCAA's side. I don't know why they haven't given that as their reason. Of course, they don't have to until it goes to court. Maybe the Sidney's had it on one of those idiot loans, and don't want to reveal they're bankrupt. Maybe they lied about their income to get it. Plenty of possible reasons that aren't related to Sidney's amateur status.
The feds already have some say in who does and doesn't get into clubs etc., even beyond the federally protected classes. You just have to not be dumb, and not give a specific reason that will look bad in court. If the reason will look bad, just don't give a reason.
About the only chance we have of the courts putting Sidney on the bball court is for a judge to look at the records in chambers and declare him an amateur. Maybe there's tax fraud at issue or some other illegality, but not payments, and that's why they won't provide them.
But the stacked deck in the courts is probably why the attorney is looking at Congress. Think Title IX. IF Congress gets involved, whatever they end up doing will fundamentally change how the NCAA does business. But that sure seems like a Hail Mary the lawyer is going after doesn't it?