No doubt he was under pressure to come up with SOME alternative explanation.
Alas, there are still plenty of useful idiots willing to BELIEVE the swamp gas explanation! Sigh.
I suspect there's a huge overlap between that group and the group that thinks Dilldo and Shrillery Clinton are wonderful people.
I've always been impressed by the photographs of a UFO taken by a Brazilian scientist in full view of his peers and a deck full of naval officers and personnel. (late '50s early 60's?)
The thing was huge, quite manueverable, the picture quality pretty good, and unlike any blimp/rocket/aircraft in either the U.S. or Soviet arsenal.
No one can explain it.