That answer would be the classic enigma wrapped in a secret and then hidden away. Now we're to the base of things: Do we believe the experiencers and then do we believe the visitors? Both are toughies.
No, unlike GingisK, I would not scoff at this concept, and I have thought of it before as well. Even if the body survives, it is widely excepted that the soul is not purely physical. If it was, obviously, it would have been discovered by now. But there is a big difference between dying by trauma or disease and decomposing, and even by burning or cremation and what happens if you are near the detonation of an atomic blast, which is far more than just heat energy. Perhaps to a secularist or athiest, the idea of a soul/spirit is comedic, but even if you are not Christian, there are a lot of other religions and even New-Agers who believe variously in the idea of souls or an after-life.
What would worry me is the question of who and why they are so concerned about the preservation of souls. It’s a very worrisome question if these ‘entities’ are not doing God’s work.
Mack, Hopkins, and David Jacobs all developed strategies for identifying people who they believed were dishonestly inventing yarns regardless of motive (whether consciously and/or unconsciously).
The stories of some publically-known people (like John Ramirez, Jim Semivan, and Garry Nolan) hang on their reputations and general credibility. I might add that the stories of Ramirez, Semivan, and Nolan are only incidental to their contributions to the "UFO/visitor" narrative and just provide interesting backstories.
What is reeeeeely interesting are the events that are said to occur at Chris Bledsoe's property down in North Carolina (mostly orbs, visitations, and high-strangeness in general). They have been witnessed by many other people and these people have gone on record.