IanW,
I sincerely doubt the vertical restriction in the airspace thru the Ukraine area where MH17 met its fate had any calculations based on engine out driftdown performance for T7's..... Their are/were numerous aircraft types flying overhead with greatly differing driftdown performance, etc.
The decision to keep the airspace open was an economic one, keep the overflight fees flowing to Kiev from use of the Ukranian airspace by air traffic. Those fees add up to huge amounts over the course of a year. Users are particularly eager to pay those fees, rather the more enormous operating costs involved in routes avoiding the Ukraine........ It all looked good on paper......