Decisions with kirk dont affect black market stuff at all so feel free to handle that situation however you want. The real deal is getting into dogtown through the dlc missions, thats what opens up herold lowes shop in the stadium. You'll find some pretty interesting gear there like kongou pistols and that order shotgun everyone talks about. Tip you might like - illegal cyberware and special vehicles with crystaldome tech are worth checking out once youre in. Just progress through the main dlc story and youll get access to the black market naturally, kirk drama or not.

Sometimes players worry about early choices closing doors but the black markets totally separate from base game stuff. Just something to keep in mind while youre doing those early missions with kirk, no need to stress about future consequences there