Logistically it would be a hassle unless you transit/fly via Istanbul or Belgrade, as the two "sides" have blocked each other from their respective airspace and commercial flights.
And then foreign-issued Mastercard/Visa/Amex cards won't work at all either. So you'd have to carry foreign currency into RUS and then exchange it for roubles.
It's a real pity the political situation ; Moscow has been on my list for a while.