<<I believe the point was that it was already at the 'unlikely' end to start with. >>
Wherever it was, the end of the U.S. nuclear monopoly made it a lot less likely.
<<I believe the US had no intention of using nukes against Russia, or of attacking Russia at all, else why not let Patton continue eastward at the end of WWII? >>
Either because they didn't have enough nukes, feared the Russians could absorb the punishment and still roll over Western Europe or because of the strength of pro-Russian feeling in the U.S.A. itself and in Western Europe. Don't forget, it took years of Cold War propaganda, McCarthyism and Red Scare blacklisting to eliminate the desire for peace and friendship with the U.S.S.R. that had developed in the U.S. during the war.
<<One way to have kept this the goal would have been for Russia to not have been so eager to gobble up eastern Europe . . . >>
What does "gobble up" mean - - push the Nazis back to Berlin? Was there some way this could have been done WITHOUT rolling over Eastern Europe? What were they supposed to do with the anti-Nazi Resistance forces in those countries? Abandon them to the local Nazi collaborators? The Yalta Conference recognized these territories as within the U.S.S.R.'s sphere of influence. Many of them had participated as Axis allies in the invasion of Russia and now the Russians had to extract reparations from them. The Allies recognized this. "Gobbling up" is just fascist Cold War propaganda bullshit. They did what they were entitled to do, took what they were entitled to take. It STILL didn't make up all the harm Hitler and his Eastern European allies had wreaked on Russia.
<< . . . as a 'buffer' against some imagined attack. >>
Yeah, "imagined attack." From a country which since the Russian Civil War had been invaded from the West by Poles, Czechs, French, English, German (twice) Canadian, American, Hungarian, Romanian, Croatian, Argentinian, Spanish, Australian and Italian armies (I probably left out a few, can't remember ALL of them) and had lost tens of millions of people as a result. That is some imagination.
<<Russia would have had nukes eventually anyway; all the spying just saved them some time doing the theoretical work. >>
Well ain't that hindsight 20/20 every time. I'm sure the Russians really knew they'd be OK if they just waited. Surely the Americans would wait for them to acquire their own nuclear weapons before launching a nuclear attack. It's the only sporting way to proceed.
<<By the time they fired their first test, we could have probably wiped them off the map if we had been so inclined, but we did not. Apparently we were not so inclined.>>
Maybe one day we'll know the real reasons it didn't happen, the explanation WHY you were not so inclined. Whatever they were, it's a cinch that benevolence and peacefulness were not among them. It would have been criminally irresponsible on the part of the Russian leaders to have gambled their people's lives on the benevolent intentions of the American ruling class.