Very very very few people who RNG are wanting to do novelty PID hunts for eggs, compared to the very frequent hack of modified captures into eggs not changing their PIDIV. The setting exists so you can change if the legality checker flags such things. I am not tuning the parse settings for "technically it is possible!" when you're already borderline cheating for meme matching PID/IVs. You RNG for resulting IVs, not for PIDs; I already know you're using an emulator with scripts, so it's not like you're doing this on legitimate hardware.
You can read more here:
Gen 3 Breeding PID Legality · Issue #3092 · kwsch/PKHeX
Gen 3 Egg PID\IV Combo Matching Wild\Static PID\IV · Issue #3894 · kwsch/PKHeX
Regarding the Gen 3 Egg Legality Issue · kwsch/PKHeX · Discussion #3895
PKHex incorrectly flagging a hatched gen 4 pokémon as illegal if its PID/IV combination match a spread that can be generated through method 1 · Issue #4347 · kwsch/PKHeX