It basically forces the whole issue. They can overturn it by throwing the entire thing back to the people with a new election.
The US does have Executive Orders, which allow the President an unspecified amount of power. These can be used to work around a recalcitrant Congress. The limits of executive orders are poorly specified, and it's kind of tossed over to the Supreme Court to figure out.
It's pretty clear that an Executive Order raising the retirement age would be rejected, since it's clearly specified in legislation. But you can never really tell for sure.
The US analogy would be, if Biden could have told the Senate: "the only way you can stop Build Back Better, is by also forcing all my Cabinet-level officials to resign"
Macron has a very useful (or dangerous) arrogance compared to other French leaders, when he thinks he's right he won't be intimidated. It was almost comical seeing him in his suit going to gatherings full of random yellow vests "taking questions" just to explain to each of them why they're wrong on national TV night after night a few years ago. Also infuriating if you disagree with him