agreed, Although I think they were in a dammed if you do, dammed if you dont situation. Especially once NATO declared that it would work towards and eventually accept Ukraine as member, which immediately preceded the invasion of Crimea.
I believe it was the lack of a solid commitment from NATO that caused the invasion, not the vagueness that they Ukraine would eventually join. But all of that is moot anyway, as the Russians where given privates assurances by Germany that Ukraines NATO bid would be vetoed and they still invaded anyway.