The moralistic argument here in France is that the AC units heat the outside air, which worsens things for people outside, especially those who can't afford AC in their home.

Never mind that these same people would go absolutely out of their minds if you suggested tearing down and remodeling most cities, which are basically radiators at night since there's concrete everywhere.

So instead of trying to somehow mitigate the issue of "AC heating the outside air", by, for example, installing the outside units on top of the buildings, so most heat wouldn't be at street level where people walk around, many people who can't breathe in their apartments just use portable ACs which dump the heat right outside their windows. Bonus points for these being very unefficient, so now electricity consumption is even higher.

In the specific case of France, they also tend to forget that most of our electricity is essentially carbon-free.