Ok but there is still the principle that a state should not join a military alliance if that would cause its neighbour to have security concerns.
No.
a) that's not a thing; and,
b) Ukraine joining anyone is no security concern for Russia, you keep trotting out that bullshit. It's a concern to Russia's expansionist strategic policies, but that's why it was necessary; because Russia was looking to expand westward.
Being required to be neutral for that reason doesn't affect the state's sovereignty.
Being required to do anything affects a state's sovereignty. Sovereignty means not being beholden to anyone.
By the way, I mentioned .. that the timing of Russia's annexation of Crimea and of the start of the special military operation suggested those were not about trying to grab more land, but about security.
And I called bullshit on that too - Russia's annexation of Crimea was prompted by concerns that Ukraine was going to be accepted into NATO, and internal political activity within Russia. It's never been about security, there was never any threat from anyone to invade Russia: Putin knows it, NATO knows it, every news organisation in the world knows (even the two that don't admit it, Fox and the Russian State Media). The only person on Earth that seems to believe that is you.
I'm not saying it's solely about the land or the mineral wealth or the agriculture, it's also about the strategic land-corridor access to the already illegally annexed territory in Crimea that also wasn't about security.
O.