Whatever Stalin did - Crimea was to that time already few centuries as a part of Russia. Russia got Crimea from Turkey at time of Ekaterina II.
Stalin did his bad things, but Stalin never changed Russian status of Crimea. It "always" (at least few centuries) was Russian Crimea. Point. Fact what at time of Khruschev Crimea was send under Ukrainian control doesn't make Crimea and especially Sevastopol Ukrainian.
If you don't like Russia you may count "Russia gave, Russia took back", But if you want to understand situation then pay attention: Crimea voted to be independent and voted to join Russia in referendums. It is the same Autonomous Republic of Crimea since October 1921.