Maybe, but i am not sure about the usefulness of discussing such hypotheticals, especially because like i said i don't think it there'd be a realistic chance of a serious defense pact happening without boots on the ground. For all their flaws in leadership i think there's a very good reason why no defense pact was signed (or ever really on the table) and also why there never was any binding agreement limiting nato expansion (no matter what russia sometimes claims). Despite the many flaws in leadership i think that at that point politics at this level did follow some rules, unlike now with Trump where nothing can be trusted anymore.
For what it's worth i assume in different scenarios there would always also be other ripple effects. Like Ukraine likely being more in the european sphere of influence. And the current level of conflict also didn't happen out of the blue overnight. Could some territory like Crimera in 2014 be lost before the slow moving west takes action? Maybe yes. But after that we would have seen more involvement than in our timeline and russia massing large amounts of troops before the most recent invasion would have also seen a different response. There are more granular levels than doing nothing and bombing Moscow.