And then they crashed it and we figured out how to make transistors from the part? And who were they picking up in 1947 New Mexico anyway? Where was his body?
The whole aliens are angels (fallen or otherwise) thing has a lot of issues. Not only do you have to prove non-human visitors, which is still pretty far up in the air, then you have to link them to the Bible.
I don't think that you are looking at this logically. - The found body, if there was one, would not be the angel, but who he had come to take or bring. The angel is immortal, and would have survived the crash easily.
Thar ya go agin . . .
WRONG.
Editor-surveyor . . . has no NEED to prove any such thing to any naysayer, per se.
He may do so for jollies or indulging silly folks or for temporary amusement, however.