At the end of GS, Mab indicated they had a mission to undertake. And with his connection to Demonreach being such a big part of his 'resurrection' I could see that being his new HQ. Combined with his newfound insight into the ways through the Nevernever, plus innate Winter Knight powers, plus the complete loss of all material connections to his old life in Chicago, setting up on Demonreach as his new home/base of operations (he's also going to be attracting a much higher level of enemy, which suggests he should pretty much be done with normal human dwellings or places of business which can be attacked so easily. TC & Ch should have been a clear indication that he had ridden that horse as far as it could go. Time to move on to a place that's much more secure and defensible, where he doesn't need mortal amenities like a job, or social security number, or 'legally alive' status to maintain.

In any event, there are all sorts of plausible reasons for both a time jump (he needs to recover from his ordeal anyway) and for him to have not gotten back in touch with his old friends for a while. At the very least, his ghost experience should have shown him that they are teamed up, supporting one another, and well-equipped and financed. They are going to be about as well off and safe as they can be, and without him bringing any of his faerie issues or other threats down on their heads. He has clearly moved on to another level of threats and enemies, and what Morgan said about him using the werewolves for support and getting Kirby killed is not without merit. Sure, he'll come running if he gets wind of a threat that's out of the justice league of Chicago's wheelhouse, which would also be a good hook to get him back in touch with them, but the low-level stuff, even as much more nasty as it has become since his death, is something they're going to have to handle on their own. Lea's lesson with Molly is also applicable here - Harry overall did better by his friends than he did by her, and that they have the wherewithal to fight back and defend innocents is in large part due to him. With the way the threats of a supernatural nature have escalated, it's going to be obvious that he can't babysit them much more, but can better serve them by helping with the big picture, and even in Mab's court, he is probably in a better position to do that.

Remember, from what Mab told him the last time she offered him the post, the motivations of her knight are important to her, and that it better serves her purposes if he is willing. She guided the events to bring him to Arctis Tor or catch the sign of the Black Council's handiwork, and she had to rehabilitate Lea from the gift she received at Bianca's party, which appears to have been a nexus of the start of a lot of plotlines that have been causing problems since. It's not too much of a stretch to say that the Black Council had a hand in that, and likely in the kidnapping of Marcone. Clearly Mab is operating against them in some way, which is at least part of the reason why she wants Harry. She has seen the downside of a knight who is working on his own agenda or suspect motivations, with Lloyd Slate, and now she wants one she can count on to at least work on a parallel track. That's the significance of all that stuff about his free will from Uriel at the end of GS. It was true, and that's why Mab wants Harry - he wants the same thing as she, on at least some level. That's also what she told him about recruiting Thomas if something happened to Harry - he would be motivated to avenge Harry's death.

All this points to whatever plans Mab has for Harry are not just going to be about BS faerie politics - there's something significant to the overall story that she has in mind for him, and that should be enough to keep him enough out of the loop for some cool interpersonal drama and reunions.