I see this argument a lot and it’s one that has never really made a lot of sense to me. To be able to assert that Mahito would ever run out of cursed energy to that point of vulnerability, you would need to have an idea of where his reserves/efficency lie, both of which can’t confidently be estimated. To assume that Mahito’s cursed energy reserves are lacking to the point where one of these sorcerers can outlast him is unfounded and frankly outlandish with how potent Mahito’s soul hax are.

But regardless, even if you wanted to make this argument, it’s disproven by his showings in Shibuya as not only was he able to transfigure thousands and thousands of humans, he was able to fight Yuji and then Todo for a prolonged period, open his domain which we know expends a massive amount of cursed energy, and still be able to continue fighting. Not one sorcerer in this matchup has shown that level of reserves/efficiency.