Colledge is a lore-unfriendly spin off made for fun mostly, so it's obivous that they will make MC immortal or something. It makes me wonder though, why in actual story the only character who was kind enough to use this protection spell is Yakuu? And if it wasn't ironical enough that actual murderer used protection spell on her slave, she used it for torturing. Why none of other guardians did that? I'm sure that at least Maryen had all the reasons for it given her situation.
Truly it feels like a major miss-step
You could argue with a lot;
>Sheina is confident she can protect the MC
>Diula(magic of different nature maybe), Naya, Madea,Margarita,Kive can't do it
>Regina isn't in a situation where it's needed(atm) +is confident she can protect the MC.
>Bevzy, Vai'Klis, Nyxmay all don't neeed to
>Kendra, Pyeka are super sadistic and Pyeka wouldn't mind just eating you if you died.
>Croixelle is unknown/doesn't need to, but it's probably because she places a lot of trust in "her people", and doesn't think they'd harm you.
>The Timfalme path is relatively safe.
But Maryen and Eliette should have cast some sort of protection spell on the MC by now, or had a path divergence where they would definitely cast one. But w/ Eliette finally getting a proper path divergence, they could use the whole not casting a protection spell to affirm his belief that Eliette is truly evil/to be feared. (and you could easily explain why she didn't cast = if the MC picked different dialogues i.eg she felt as if the MC wouldn't want that/she felt very comfortable)
Maryen though would do it to protect the MC from her other self, especially if you choose the dialogue that has you reject her other self.
And even if they can't do it personally(very unlikely), they DEFINITELY HAVE SOMEONE TO ASK.