In my post I was talking about a prey spine puncturing the predator and emerging out in the open.
I think the case you are asking about is how the gulper survived when the TSN it ate poked its whole skull out the gulper. First, IDK if this is true that the gulper lived, I am not quick to trust people's word, especially those people who I don't know and who are YouTubers. Second, if it did live that'd be miraculous in my one-page book but it could be also because of my ignorance, maybe it is not so unusual for gulpers, it's a very specific area to know anything about.
Have you done a search for this? Google, forums, fb, mfk, planet catfish, etc.? We need more data.
What I reported with attu and wyckii happened in my tank. As the attu kept digesting the wyckii, little by little the spine was withdrawing inside until it disappeared and the hole closed up quickly and healed.