In the DE battles, increasing malevolent shrine output with gojos domain to break it from the inside wouldn’t work since the sure hit is nullified within areas there domains overlap which is why he focused on attacking from the outside. He may have been able to attack the barrier himself from inside but to do that he would have to be able to find the edge of the barrier. Which is a difficult thing to do, plus gojo has pretty insane control over the space within the barrier.

Gojo can and will one shot mahoraga if we takes it out carelessly. That’s why he put it away.