Humans don't have absolute knowledge, which does not mean they have no knowledge at all. Imperfect knowledge does not mean no knowledge. And lack of knowledge is often preferable to anti-knowledge.

Humans have some, albeit imperfect, knowledge of reality. Some things are unknown and some of those things unknowable, but some things are known to be true and others false. Again "known" does not mean imply absolute knowledge, but "correspondence to the facts."

Not all knowledge reduces to mere opinion.

TM adherents (to include MMY) have indicated in the past that yogic flying included corporeal levitation (not just "spiritual" levitation but physical levitation as the video reveals).

Those people (including MMY) are full of crap.