Oh, not saying it doesn't make sense. It does, from all of us.
But this is the first time that my character's being ethically at odds with the team can cause a rift. Thinking how to play it out. Because even if the kobolds here turn out to be evil/bad, Zesty has interacted with the Dragon's Rest kobolds enough to feel they are the victimized here, even if you've intimated they are the aggressors.
Zesty is smart. Especially after the kobold's turn, it's clear they are serving an entity. As the Dragon's Rest ones serve Runara/Bahamut/bronze dragons, these are clearly sided with some blue dragon/entity that Runara alluded to. Since this is a good/evil thing with the dragons (again, as Runara explained), there is almost a clear indication these creatures are "bad" or sided with the baddie. But they are also sentient creatures with skills, personalities and abilities. The Owlbear is a predatory and dangerous creature. So, Zesty wants to save the kobolds because they could be of use if nothing more. This isn't the end boss, and clearly making good with them could lead to opportunities. Wiping them out because we want play time with a predatory creature turns Zesty.
Like the merrows and harpies before them, sentient creatures often will give us more dialogue and information, and he is literally watching his whole team actively trying to kill the sentient creatures in favor of TV Funhouse. So now he has to think how this affects his relationship with his team.
Hey, backstory, friends! Shows I AM thinking about this shit behind the scenes. I'm enjoying this!
