That ‘referendum’ back in 2014 was a total sham — but even still: should Mexico get Southern California back just because enough Mexicans vote to make it so?
The move was no different than Hitler’s anschluss of Austria. Or the Sudetanland.
Russia has had a navy base there since before Ohio was a state. There was zero chance they would ever allow it to become a NATO navy base.
Bonus question, in 1853 Britain and France and the Ottomans invaded Crimea and blockaded Sevastopol.
Do you know who they wanted to drive out of Crimea?