...he posted that 3 days after the invasion, 6 days after his previous tweet, and hasn't posted (including likes or RTs) since though he was posting multiple tweets a day on a wide variety of topics up until stopping 3 days before the invasion.

I mean, unless he had a much broader epiphany and you mean literally everything when you say “things he does not understand”, the tweet you reference, and your (reasonable) characterization of it's overt message read in isolation, doesn't really explain his actual behavior change.

EDIT: It's also worth noting that his next to last tweet, on the last day he tweeted before the six-day pause, was a vague (generally taken as negative) post apparently about Putin’s speech the same day: https://twitter.com/Snowden/status/1495848959335706630?t=QSI...