In a normal situation, this situation shouldn't happen. Mother High Heaven was supposed to kill the Will of the Tyrant Realm and absorb what they needed for the realm tree to detach from the law matrix. This would lead to the destruction of the realm and leave nothing for the realm lord's enemies to do.
But Legion has brought the destruction of the Tyrant realm forward, before the death of the Will of the Realm. This would be a good thing if Legion didn't do so while removing a large portion of the law matrix of the Tyrant realm from within, thereby reducing the support of the void universe for it. This created the opportunity for the enemies of the realm lord to interfere.
Tssandulighafan is very strong, that's why he was the first to break through the barrier. The barrier might be weak, but the protection is still there, so there is a backlash to the world gods that attempt to break it.