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.
Sweeping statements in biochemistry must be made with caution. It is well known that there are some small peptides that are absorbed following oral administration.
...BPC-157 itself is said to be among this class. As are certain milk tripeptides: https://en.wikipedia.org/wiki/Lactotripeptides
Interestingly enough, those two, as well as Gly-Pro-Hyp, are proline/hydroxyproline-rich, which might suggest that proline-rich small peptides are resistant to degradation in the gut.
Anyway, in general oral proteins and peptides are broken down prior to systemic absorption, but not always...
Here is the exact quote:
Every single YouTube video and blog post I have read about peptites is exclusively about injectable supplements.