Vindman is Ukrainian, not Russian. But yeah, your point still stands.
He was born in Russia [Soviet Union] before Ukraine became a separate nation,ergo Russian.
Ukrainians were a separate ethnic group/country/nation long before the Soviet Union existed. Same as Tajikistan, Kazakhstan, all the other 'Stans', Romania, Bulgaria, Lithuania, Estonia, Belarus etc. etc....but as I said, your point about foreigners(or any others) who's loyalty rests outside our borders should not be allowed in our military, is spot on, and for obvious reasons.