alt Hacker NewsFor the first one, I assume you mean a systematic review, not a peer review? I guess you're talking about this one:
https://pmc.ncbi.nlm.nih.gov/articles/PMC10180699/
It has a Mechanism section which explains that when collagen is digested, one of the products of that is Gly-Pro-Hyp, which is what has the effects. I don't think that conflicts anything in this post?
I assume they're referring to the brief bit in the post that indicates that oral ingestion leads to a breakdown that makes oral supplements of amino acids pointless. They say it very briefly and they don't really outright assert it, it's just a sort of implied aside.