Courtesy of this answer on Travel.SE, most foreigners aren't allowed to cross from mainland Ukraine into Crimea, with a few narrow exemptions, at least as of 2015. Procedure for entry to the temporarily occupied territory of Ukraine and exit from it mentions diplomatic and consular functions, journalist activities, and religious activities. So someone couldn't go to Crimea just to experience Crimean Tatar culture as a tourist, or learn the Crimean Tatar language, as far as I can tell.
Why are the exemptions for travel so narrow? What's the rationale?