The only way to currently access Kevin's shop in Foundry is to talk to Dan and ask him about Foundry. However choosing to ask about Gorsky or the beast first permanently removes the option to ever access that shop.
Losing an entire weapons vendor because you started with a different dialog tree is just bizarre mechanically and really hurts when you're trying to offload items.
Dan could keep the option where ever he may be, or you could need a higher check at Kevin/Chief of security, or it could be unlocked automatically as a reward for helping out the Foundry.
Really, any other way to access that shop, no matter how roundabout would be ideal.
