Here’s another way of saying my objection to your original comment: What makes “happiness is intrinsically good” more of an axiom than “sufficiently intense suffering is morally serious in a sense that happiness (of the sort that doesn’t relieve any suffering) isn’t, so the latter can’t compensate for the former”? I don’t see what answer you can give that doesn’t appeal to intuitions about cases.
Here’s another way of saying my objection to your original comment: What makes “happiness is intrinsically good” more of an axiom than “sufficiently intense suffering is morally serious in a sense that happiness (of the sort that doesn’t relieve any suffering) isn’t, so the latter can’t compensate for the former”? I don’t see what answer you can give that doesn’t appeal to intuitions about cases.