Would the Warsaw uprising become known in the Allied media early enough for it to take on the character of 'fact'? Stalin was fairly clear on whom he wanted to run things in Poland, so if his troops meet Polish partisans in control of the city but with little or no contactwith the outside world, he would very likely order his troops to disarm them and, in the event of resistance (even odds, I'd guess) kill them. Obviously, they were Nazi sympathisers at heart, resisting the forces of liberation entering their city...
If the victorious uprising was known well enough in the west to take on a recognisable 'catchword' quality, Stalin may have to bite back his instincts and accept the Polish 'Army' as Allies. He's still likely to make life difficult for them (I'm sure there are enough people in the Polish exile government in Moscow all too happy to oblige), but slaughtering heroes may just be too much for the West to stomach.
Didn't the Soviets have their own 'Polish People's Army'? How about he insists on brigading the two together, relying on the pulling power of the uprising to attract recruits from among the Polish partisans and manipulating the command structure to put his own brand of Communist in control? There were enough Nationalists and Democrats prepared to cooperate with stalin at the time, believing (against all evidence) that he would return independence to their nations or resignedly recognising him as the lesser evil. I'm sure a number of missions could be found for particularly troublesome personnel not to survive. Although, given Stalin's usual habits, there'd more likely be a few treason trials.