I fail to see what this has to do with the Baltics, which is what you asked about. Ukraine was making plenty of overtures to NATO and NATO's continued encroachment was definitely a threat to Russia. I'm not sure how you can so definitively conclude that Putin was not worried about this encroachment.
Edit: I mean, just look at the recent history of Ukraine's friendly intermingling with NATO just prior to the invasion:
You can certainly argue that this was just an excuse for Putin to invade, but there's little evidence to be so confident in that conclusion, and plenty of countervailing evidence.
Edit: I mean, just look at the recent history of Ukraine's friendly intermingling with NATO just prior to the invasion:
https://en.wikipedia.org/wiki/Ukraine%E2%80%93NATO_relations...
You can certainly argue that this was just an excuse for Putin to invade, but there's little evidence to be so confident in that conclusion, and plenty of countervailing evidence.