Halsin is the obsessive type, which is a bit at odds with his stories of wild adventurers in his youth. But people can be complex; I know I have fond memories of somehow surviving my youthful adventures without wanting repeat them. My feeling at the end is that he is finally doing something HE wants instead of what is expected of him. And as a druid, he is devoted to serving nature as much as a cleric serves their god.
I'm a fan of character agency, so I don't feel Tav should be able to talk him out of his desires. (**see below) There are other companions where Tav basically decides what they will do, and I find it icky. But it would be ideal if Tav could talk to him at the party about spending more time out of the community, getting some time in the wilderness together. Especially if Tav is a druid. I am 99% happy with the end but I realize no ending can please everyone.
In Karlach origin romance with Halsin, he says that his community may grow able to stand without him and then he would join her. So he isn't necessarily planning on being there forever.
**One thing of note in the datafiles:
There is an impossible to reach dialogue where Tav says they will join him right away and Halsin is surprised Tav would even want to come with him. It's another reflection of Halsin's self-esteem issues.
"Devnote: Taken aback/doesn't dare to hope the player is serious"
