It is by no means clear that Russian military/state will “win” long-term in Ukraine. When there is significant local opposition to military occupation, it is indeed hard to maintain control.

But in the mean time, they’ll be able to kill a whole lot of people and destroy a whole lot of lives, and wreck Ukrainian democracy and economic prosperity for years if not decades.

US has something to lose. That logic doesn't apply to a caged animal.

...Afghanistan isn't a nuclear state

I think he was characterizing the US as the nuclear powered thug.

Or the USSR as a nuclear powered thug. Afghanistan has a decent track record of beating out superior foreign occupiers.