I actually liked it in the drama because it felt like they subconsciously responded to his authority and competence

That's true. That's very good. And there is some resistance to him joining the team (or maybe I read that in a fanfic), so that helps too. Plus, he's been helping out on cases for a while by the time he's officially onboard.

I thought it was definitely about their relationship, and that ZYL is actually a bit insecure about it, not really trusting it'll last, despite his surface behaviour. It just comes out in the worst way!

*nodnod* If ZYL is acting out of insecurity (being all Zaphod Beeblebrox slightly-out-of-control) that makes it a lot better for me. :-)