Well, I have some co-workers in Ukraine I was working with on a daily basis for two years (remotely) who would disagree with him.

One of them had to flee to Poland with her kid in the early phases of the war while her husband stayed behind to fight. Others spent hours on end putting Molotov cocktails together so that they could throw them at Russian tanks if they entered Lviv, a real possibility in those days.

I think there's a valid point to some degree that NATO expansion was a little hasty, but the brutal invasion of Ukraine was an overreaction. The folks in the Baltic states had legitimate security concerns, which is one key reason NATO expanded. So did Hungary and Bulgaria and others who felt threatened by Russian history.

And as another commenter mentioned, the invasion was a clear attempt by Putin to rally his populace around the flag of Putin.

What Mearsheimer should have said was that the invasion of Ukraine was indefensible, just as the destruction of Grozny was years before.