Choosing the alien over the other.
It's very believable that he had issues with "frowzy corrupt air."
If your job is 'rescuing people,' you sorta need to do it right the first time.
Your grandparents were arguing about the same things.
Turns out those things have a pretty sketchy history.
This is a story about time machines, aliens, a lot of dynamite, hermits, and a giant rock.
Sometimes people just roll up to a random island and scream, 'This is the REAL Garden of Eden!'