If that thing crashed into my home and damaged my roof, Id make sure there was a written contract stating the piece cannot be damaged or altered from its state and that once any testing or studying is done with it (within a reasonable amount of time, but clearly defined with a number such as 1 or 2 years at most) that it must be returned to me.

It wasn’t supposed to survive. They willingly tossed it away as refuse and it landed in his property. It belongs to him now if he wants it.