He didn't "flee" to Russia. His passport was renounced/revoked/disabled while he was on his way to the original destination. He got stuck in the Russian airport for a freaking long time in a small room while the govt made sure he can't go anywhere else. Good Lord, fled to Russia it seems.
He could have returned to the US. He chose to exile in Russia. He was already fleeing. I posted a bunch about it below
That's how it looks at least. It's a good excuse if your goal was always to flee to Russia.