Earlier quoted context omitted.
It would be a serious problem for NATO if a pro-Russian Hungary could basically act as a fifth column and cripple NATO by vetoing everything. There simply has to be a process to kick out insincere members.
The issue with kicking out members is that it starts a precedent. The idea is that NATO got your back if you're in, you won't get kicked out if your membership starts being inconvenient, and that the other members will act when Article 5 is invoked.
None of that is violated by kicking someone out before they are attacked.