You have a valid point about Texas. However, the equivalent would be the following:
What if Mexico moves 20 million people into Texas, and holds a referendum for Texas to join Mexico.
Russia moved people/troops/infrastructure in, and is forcing a region to vote to join them.
It’s a hostile takeover/invasion of a region.
ie, it’s not Kosovo, it’s Kuwait.
Russia already had people/troops/infrastructure there from way back. Most of the people of Crimea are culturally Russian and speak Russian. If they want to be independent, who are we to say yes or no?
Who appointed us the decider?