If Mr. Castello wants his story to have credibility then I make this suggestion.
Fearing reprisal while he lives in exile is understandable.
However if he is terminal, little can be done after the fact.
While alive he should prepare as much documentation as possible to verify his identity and his claims.
That is what I would do if I were in his position.
I would probably go totally public as soon as I was diagnosed as terminal.
What would there be to stop me, fear of dying?
I have little fear of death now, it is certain anyway.
Once it becomes imminent, little to lose, so if I had a big secret, I would go all the way with identity revelation and everything.
But thats just me, and I have had enough close calls that, I have been there.
I just don't have any earth shattering secrets. Wish I did.
Whatever works, use it.
A good idea stands on its own value independent of authorship.
If it stands or falls on the credibility of the author, maybe it isn't such a good idea.