Sorry, but I'm with Wilder on this one. On his side the contract is legally binding, on the team's side it's a piece of toilet paper that can be flushed any time, if they no longer want / need his services.
Other CFL players have been released so they could take a shot at the NFL, which does create a precedence, which by the way can become law if it happens often enough. Just ask yourselves which scenario is more common: giving players the opportunity for an NFL shot, or forcing them to abide by a contract that the other side can thrash at any time.
As for the NFL not being allowed to speak to Wilder while he's under contract, methinks the CFL would need to get their own house in order before they tackle that issue. Let's not pretend it doesn't happen before free agency in the CFL - it's obvious that it does.
This does not look good, and it is not a good way to encourage talented players to come to the CFL.