"The Singularity being a priority to them is why I want to be here right now." Despite him and Lucifer talking about where they could make a new life, that is a 'down the road' possibility, not a next month one. Maybe when they have answers and anchors and can take a break. Istredd would not leave Thorne tomorrow if given the option. He will have no better access to the information he finds vitally important.

"If we weaken the crown too much, it weakens that protection too." Istredd is not saying they should bolster the crown of ignore the reasons and ways they can break it down instead. Those are all pertinent ideas. But priority wise, if the Singularity becomes vulnerable, the Free Cities may fulfill their threats. It is a tight rope they're walking.