But the decision to apply or not was theirs and other NATO members welcomed them exactly because that was conforming to NATOs values and principles.
Most tellingly, these were countries that were in a similar treaty before with Russia - the Warsaw Pact. The one that crushed the Prague Spring. They knew exactly what the difference between the two treaties were.
It is common practice, after big wars, to negotiate what newly created states can or cannot do, this was done in Europe for centuries (Belgium, Poland were often under such constraints and used as buffer zone between empires).
What treaty are you referring to?
The US has been working on surrounding Russia with NATO states, putting bases and nuclear next to Russia, Russia tried to do the same in Cuba during the cold war but the US did not accept it and was ready to sink the Russian ships, Cuba was "free" to do that but that doesn't matter because the US beleived it's a threat. Now that Russia beleives it's strong enough to face the US on some small issues (the US is still much stronger but not as before) it no longer accepts to have NATO on it's border, especially in Ukraine because historically that's where Russians come from plus it would hurt their access to sea.
Anyways, that's how it looks like for me as a bystander.