Why not? They're dirt cheap right now and eventually things will straighten out. I would buy more if I could but I'm not allowed to right now ;)
You buy a stock for the future cash flows. Right now, there is no future cash flows by definition. You would only hold onto russian securities if you are taking the bet that Putin falls.
Might as well just go buy lottery tickets. Less risk.
May as well hold on to these assets then. What else would you do with them?