AFAIK, the situation with Burger King, is that unlike McDonalds, BK doesn't have much leverage over Russian franchisee's. They can try and say "close the stores, we're leaving", but the actual store owners would just say "no" and re-brand them back to "Rostik's". They don't really have any assets in Russia so there's nothing really to sell either, but they do still receive the franchise fees. So pulling out would only benefit Russia
Rostik's is actually what KFC was, and the funny thing about it is KFC has the similar franchise structure in Russia, they officially left, told all franchisees to change names back to Rostik's, but the biggest one just said "no" even to that, as KFC's contract that includes the rights to use the name expires only in 2035.