“Not true.”
Really? So you are saying the annexation in 1954 during the Soviet Union never happened?
Crimea was already annexed by the Russian Empire and then the Soviets about 200 years and got transferred to Ukrainian SSR in 1954. Administrative, not exactly annexation.
If Crimea didn’t have the option of leaving Ukraine when the Soviets collapsed, then your point would have some justification.
But they did. And they chose narrowly to remain as part of Ukraine rather than becoming independent and probably end up joining Russia again.