Concede what ? I've read the entry and I've not seen anywhere where it states he takes missions?
Your argument was that he wasn't a main branch
and on the mission aspect the fact that he wears Konoha attire, something Hiashi didn't do until the war and the fact that he is a Jounin means that he needed to again approval from the Daiyomo
nowhere does it say or show that a main branch member never needs to do missions
your argument also has no basis that Ko Hyuga doesn't do missions either since we lack any screen time of him.
But unlike Hanabi that has a job to become heiress, Ko and other main branchers likely have other jobs to do as they are part of the Konoha shinobi force.
We also see Ko having the uniform and being engaged in the Pain invasion even though Hiashi was out of town. Meaning he took orders from Tsunade.
Again unlike Ko, Hanabi was only shown to be home schooled... as in we never saw her dawn the genin,chunin, or jounin outfits
She might be a jounin now but we unlike Hanabi, Ko isn't in line for being the head and thus like the other Jounin Hyugas do other things.
Also a databook apparently isn't verified
...okay