It is not about Halsin, Zavlor or any other companion. Is is more about certain companion archetype game is missing -- a friend. Pure friendship without any sexual context. An example from Dragon Age universe Varric. There is lore behind why he can't be romanceable. You can say that bg3 has Jaheira and Minsc, but they are added to the party too late but are more on their own.
I could see my half wood elf Ancients paladin being bros with Halsin, if he kept his nose where it doesn't belong. But that just adds further frustration to this whole situation, because it could have been cool to get to know Halsin more and become good buds. It's just that most people aren't cool with their friends trying to bang their girlfriend.
