NATO can change the rules anytime, from the russian perspective you can't trust them. That is why russia wanted an official stance of not admitting them. If they were not going to admit them then why not say so out loud. Clearly their was a way to solve this matter peacefully but the west choose to ignore any demands for neutrality
Memberstates might be amenable to vow to block certain admissions, or maybe not.
There is zero chance of an unanimous vote to admit a country that has open territorial conflicts with russia.
Its not within the power or responsibility of NATO to decide about ukraines neutrality. The charter of Paris, Budapest memorandum, https://www.nato.int/cps/en/natohq/official_texts_25468.htm .. (russia signed all those) all guarantee ukraine a free choice of military alliance.
