It's not as ridiculous as you think.  Every province in Canada had to get incorporated with a separate piece of legislation, and not all provinces signed into law the same strictures on their incorporation documents.  NB, NFLD, QC, etc. didn't have a guarantee in their provincial documents for a separate system, so when they decided to axe it, they had ONLY the federal constitutional documents to fight.  They argued that education was provincial jurisdiction, not federal, and bingo bongo, they were done.

But ON, SK and AB have a separate system guaranteed right in their provincial incorporation documents.  Any removal means a court challenge on provincial legislation, in provincial court, on a topic that's provincial jurisdiction. The single best argument, the one that one the cases in those other provinces, can't even be used.