So, does he believe these, or just open to the ideas/discussion that they are a possibility?
There is a lot of "Could have happened" that we can't prove or disprove.
Emphatically saying something you can't prove isn't so might be off the rails as well.
Some things just open themselves up to conspiracy theories.
I know a guy that is runs a decent business, dead convinced though that big oil had the government assassinate a guy with a special carburetor design that would run on water. He was silenced and his workshop confiscated to keep demand for oil from going down.
It doesn't seem to matter that chemically it takes energy to separate water into its elements, making anything running on water a loss.