While the school may grant you a release, the conference may be another story. They may have the ability to have you sit out a year if you transfer to another school within the conference. Just as the SEC did with the Fagan sisters after their departure from Florida.
You a absolutely correct, but the Fagan sisters deal at Florida and this Mizzou deal are completely different circumstances.
In this case, I bet the SEC will allow anyone wanting to leave an unconditional transfer.