That sounds a lot like strategic secessions... If this wouldn't be, I have a hard time seeing what would.
Strategic Secessions usually involve a war, the new realm isn't at war with anyone. The aren't going to be getting a capital closer to a war front.
From the wiki "Strategic secessions are prohibited. This means creating a new realm, through secession, in order to circumvent recruiting-in-capital-only restriction. Friendly secessions are okay."
The issue the realm is facing is one of control, there regions are too far flung to reasonably be able to expect to hold all their regions without tons of court and buro work.
