Okay, forget that whole Sharon Waxman-suggested scenario about Paramount chairman Brad Grey hesitating about bankrolling Mission Impossible 3 because of…well, Waxman vaguely implies this is due to concerns or at least questions about Tom Cruise’s recent oddball behavior. A seriously informed source says the reason why an un-named Viacom executive told Waxman that “no definitive decision has been made” about M:I3 is because of…ready to be surprised?…Cruise’s deal. Specifically, his “massive and unreasonable” back-end deal, which is around 30% of the first dollar. (He doesn’t take upfront cash.) With the budget of M:I3 pushing toward $180 million (yup, that’s what I’m hearing) and with a first-time director (J.J. Abrams), Grey and Co. aren’t anxious to pay off a monster-sized deal that was made by Par’s previous regime. “And they really will pull the plug if need be, or so goes the talk,” my guy says. If you really want to get tricky about it, I guess the Cruise-acting-slightly-wacko theory plays into Par’s court because the more this viewpoint gets around, the weaker or less together Cruise appears to gossip hounds as well as certain Scientology-dissers in the press, which eventually seeps down to the Average Joe’s and translates into a general lowering of Cruise’s stock due to everyone going “what’s up with this fucking guy?” and this, finally, bounces back into Cruise’s corner and his agents have to lower his price because their client has backed them into a corner without a strong hand to play.