Sir: Yours is the most logical explanation I have heard so far. I don;t think anyone who runs a SAM battery is targeting an AN-26 at 33,000 feet. I worked woth the Ukranian and Russian military and they’re not that dumb.
they would also need early warning radar data and communications from much further out (ATC? military radars?) that this flight was enroute
aiming shooting and firing these SAMs is not a spur of the moment action