The largest documented forensic analysis project in history, yet nobody knew what they were working on, and thy couldn't tell from the bone fragments the whole thing was faked in some offsite location with hatchets, cleavers, meat grinders etc.

They got all those people off the plane, processed all those the bodies, scooped it all up, drove it all over, and started scattering it all over the place amongst fake debris.

Sounds like a bullet proof plan with no hopes of being found out.

How far fetched does it need to get to uphold the magic missile?

Pretty far it seems.