That is not a civilian airport but a military airbase and it is not an airline or private but Polish Air Force One plane landing. I think it is incorrect to apply civilian rules there. I really doubt a military ground control may be authorised to close a runway for a friendly Presidential jet flown by another military aircrew. They may advise them to fly to a safer place but they know the pilot is on duty under order and it is a pilot who has to choose does he able to land or not in such a condition. Same about the language they are using. it is not a civilian airport and not a civilian airliner. If they were choosen to speak Ugandian or Russian it is their own business.
I think there is a few place for a conspiracy.
They were speaking English - The Russians went to speaking Russian at the last point when they were off their glide path..