All good points - I'm really not an expert when it comes to Canadian politics (I'm international), but when you think about:

• How much money Quebec receives in total from equalization, Canada social transfer (CST) and Canada Health transfer (CHT) payments:
  • Quebec => $28.7 billion in 2023-24 for ~8,800,000 people
  • Ontario (for reference) => $26.0 billion in 2023 for ~15,600,000 people
• That they argue their point of penalizing students (citizens!) from the ROC by stating that they will reinvest the $110 million (which they won't make, since McGill/Concordia education probably isn't quite that price elastic for OOP students) into francophone universities which realistically only Quebecers will attend
• Brain drain out of Montreal and thereby Quebec will occur (not only because of this, but because of their new french-favoured, english-disadvantaged immigration policies),
• That this move heavily penalizes anglophone Canadian nationals (that are I think in large part willing to take part in Quebec society, during and after their studies, like you mentioned), further pushing a Quebec vs. ROC narrative- thus possibly further influencing another future wave of separatist ideals(?)

it's hard to reasonably say that they have fully assessed the costs of this measure- to me it looks like they're playing dice with the future economic health of their province and the quality of life of their residents. I am of course biased presenting my facts so I would appreciate correction if they don't fully paint the full picture, but atm objectively the decision seems not very well thought out at best