The central theme of Hart’s article is that the world qua God’s creation is an expression of his perfect goodness and rationality, and that eternal damnation would be incompatible with that perfection. Of course, defenders of eternal damnation like Aquinas would deny that there is any such incompatibility, for reasons like those set out in my earlier posts. So, Hart owes us some argumentation in addition to this assertion of incompatibility. And indeed, he offers (as far as I can see) five lines of argument in defense of his position.
“Who among us can dwell with the devouring fire?
Who among us can dwell with everlasting burnings?” (Isaiah 33:14)