But such a conclusion is simply not warranted. The fact that "the God helmet" triggers such experiences does not entail that the brain is the origin of such experiences. For example, one could be blind due to damage to the brain rather than the eyes. One could thereby restore vision if that part of the brain were altered to make it fully functional again. It wouldn't thereby entail the things we see are not out there.
The brain might prohibit such mystical experiences in its normal functional state. Altering a certain area might allow us glimpses of a reality normally inaccessible to us as the brain filters out such experiences.
See other essays by me on this topic in my other blog: e.g