.....the testimony you are referring to is like these clowns claiming a UFO picked them up--
...it is not verifiable
Grin. This is much closer! We can all relate to dreams that are incredibly life-like, and some have hypothesized this might explain what happened. Some, of course, are a bid for attention. The same is true of experiences of God, angels, near death experiences.
The brain is an amazing and complex organ. If anyone were to tell you of a UFO or a supernatural experience and attribute it to the brain processing data in an unusual way, most unbelievers would immediately accept this testimony.
It is when the testimony includes aspects that cannot be explained by a brain glitch, that unbelievers cry foul and cry, "No physical evidence!" which is the narrator's point from the beginning--thus the reason for their account or testimony.
Perhaps your argument is, "Anything that cannot be attributed to a physical source (i.e. the brain) should not be classified as "testimony." ?