I believe I understand the logic of your point. It’s fascinating.
Still, I would think that repealing Obamacare is only one of many possible approaches.
Couldn’t the congress simply amend Obamacare and effectively null it without declaring the original legislation unconstitutional? Or replace it with something else?
Another approach would be to simply refuse to fund it. I would guess that would be within Congress’ scope of authority (obviously this would create a mess because the law would still stand).
The bottom line is this: the requirement to state a constitutional basis for every bill introduced, though it sounds good at first glance, may have undesirable consequences in certain instances.