BG3 is already expected to allow 4 customs, at least for multiplayer. And hasn't it already been shown that Lae'zel and Us join your tutorial party with no problem??
If GM4Him is arguing for the option of playing with 4 customs + 2 Origins, but you can still play with 1 custom + 5 origins, then that's fine. (I assume this is what you mean?)
If he's arguing for that being the only way you can have a party of 6 is that you have 4 customs, then no, hard disagree.
