If there's a clause allowing him to speak to other clubs, there's nothing no one can do, except MR, if that clause is met.
I think here you are incredibly short-sighted, what's, say 500k (if we're lucky tbh), to the 10s of millions the owners have put in, if we get promoted we get millions, not hundreds of thousands, and lets face it, even the most biggest cynics of SISU will admit they would acknowledge this, with MR we have a chance of promotion via playoffs, but if he leaves, will the club have another period similar to Shaw's whilst we wait for a manager? We could still get promoted without MR, but, it's going be less likely.
You like your conspiracies don't you?