There is no credible threat of a NATO invasion but there is the First-Strike issue now that hypersonic missiles are being developed. Putin has been moaning about this for a while now. A security-conscious/pragmatic state models "what is possible" vs "what is probable". If it seems likely that future Finland could host hypersonic missiles pointed at St.Petersburg, well it becomes incumbent on Moscow to attempt to prevent that. It seems unwise to dismiss their concerns if said dismissal would lead to Ukraine 2.0.
Lots of people seem to think that the Russian unwillingness to flatten Kiev means they could not do it.
How many people have to die for Finns to feel like they stood up to a bully?