answered:
America would’ve won a total nuclear war in 1951 and MacArthur shoulda forced *Truman* to resign
Interestingly I’m not sure this would have left America in a stronger position going forward – the old European empires hadn’t fully collapsed yet and in the absence of Soviet counterweight could plausibly regroup, and other Cold War positions hadn’t been consolidated yet – Indonesia didn’t purge its communists until 1965.