Truman would have had to have OK'd the Nuke. Remember this is in late 1950-and at that time the Russians only had a few nukes compared to hundreds for us. We had the B 36 in service at that time and were capeable of reaching most of the Soviet Union and hitting the targets, while the Russians had nothing capeable of getting to the continental US. I think that Stalin would NOT have taken the chance to openly fight us. Now he would have supported China for sure, but that is all. The mass human wave attacks of the Chinese Army are particularly vulnerable to nuclear strikes since you have to mass the troops before you attack.
Now the implications of using Nuclear Weapons at that time are hard to figure.