They should; I’d make it an expensive little present for the Kremlin.
All of Crimea’s electricity and water, and a huge of its food, come from Ukraine.
Cut it off. The Crimeans want to annex themselves to Mother Russia? Fine....then let Mother Russia supply them with potable water, with food, and with electricity. Oh, and blow that bridge that connects Crimea to the rest of Ukraine as well.
There you go, Mother Russia....enjoy looking after your new children; now as helpless as infants.
The Russkies have no intention of stopping at just Crimea or even Ukraine. They want it all.