Eight ball yoda says… bad trip sitter he did seek, hmm?
First it makes people purge (vomit profusely) because the MAO enzymes normally break down the psychoactives in the stomach, and it reacts violently when the enzymes are inhibited with MAOIs. It's likely a reaction to something else in the plant because the psychoactives absorb into the stomach before they throw up.
The technical name for what happens next is "full disassociation" which can best be described as the brain disconnecting from the sensor organs and then hallucinating whatever it wants in their place. The actual experience people have varies all over the place. Lots of trip reports of people seeing god, or aliens, or seeing their life flash before their eyes.
It's popular among the Silicon Valley crowd in general from my experience, but specifically the ritualistic experience in the Amazon. Freebasing DMT isn't as popular.
Ayahuasca (and DMT for that matter) tend to make people not care about anything, so I wonder if he did some and has been affected by it. Just a guess, though.
I know a lot of people I would be wary of if they were to consume psychedelics, given how they already act towards people with restraint.
Generally the critique is that it leaves one too unchanged. It's all sparkle and no lasting insight. Fun, but otherwise kind of pointless. Like it's missing its other half.
The Ayahuasca comments in this thread are the people putting their own narrative on it, and as the OP of the thread, this was not my intention at all. This thread has just become made-up gossip.