Removing wreckage to hide cause of accident as described by US politicians?
Not by US politicians but by OSCE who observed the scene. You don't move actual hardware pieces around unless investigators tell you so. And specially if you are "poor", with dilapidated equipment you don't volunteer and move things around, right?
Maybe they or their government just don't want to go into a war zone
maybe they don't want to be pushed around and micromanaged by masked commandos who tell you where to look and where not to look and look at their watches and tell you your time is up.