Meh, IMHO the actually important rule is that parliament has to consent to the PM. He appointed someone else that had a majority tolerating him, and then parliament changed its mind and now Macron has to pick someone else. The left only has a plurality not a majority. Why should that guarantee they get to pick a PM?
If the results were 30% centrists, 30% leftists, 40% RN would you be calling for a RN PM?
Macron chose someone from the lowest-vote party (LR) to spit in the faces of the voters. The largest bloc was leftists, so they should have gotten an opportunity to form a government. But even if he decided his future was with the extreme right, choosing an RN PM would have made sense.
But no, he chose a personal ally who nobody liked.
If the results were 30% centrists, 30% leftists, 40% RN would you be calling for a RN PM?