Comin' back to the idea of Kellogg realizing once him and Synth Shaun are assigned to live in Diamond City, barely fifty feet away from the site of the Broken Mask, it's only a matter of time before they're sniffed out by Nick or Piper. He's not at all considering Sole showing up as a factor here.
Kellogg meets with Nick and begs him to help them hide, framing it as a protection job he's taken, keeping a kid being fought over in a custody battle safe until the relatives unfit to care for him give up. He's caught onto the Institute looking to get rid of him and talks about it with Nick with the same plodding certainty as a terminal disease. Nothin' we can do. Please, just give me this before they terminate me. It's the one thing I can make right.
Would Nick's sympathy for the kid and the merc override his concern about Kellogg's true motives?
Nick raises an eyebrow a bit at the claim he's willing to do "anything", Kellogg reassures him that yes or no he'll keep the choice a secret, I know you value your privacy highly.