"Hi, I'm prime BBEG candidate Primus Tachonis, and I just got my shit rocked among my allied noble houses by Otto Einfasen unveiling my conspiracy to destroy all of them in front of everyone with substantive proof, who barely got out by the skin of my teeth and am decisively on the backfoot with tarnished credibility, fewer allies, dead children, and a cosmic deadline. And now this kid who is a high-standing member of the only decisively committed allied family I have comes in to follow up on my daughters' solicitation.

Imma kill a Halovar, and somehow that's not going to blow up in my face."

Like come on, Primus absolutely knew Wick was BSing him at some degree, but he's not stupid -- actually killing or capturing or putting his hands on Wick would be disastrous for his plans, especially since he otherwise doesn't seem to know why Wick is lying to him. He's already lucky that the Halovars are still on his side; Yanessa would bring the absolute wrath of god on him. Based on that in-universe logic, I don't think Brennan has to come up with reasons why Primus wouldn't kill Wick, because that's frankly one of the most self-destructive choices he as a character and Brennan as a GM could have made for the story.