One big stumbling block in negotiations is teacher recall. The union wants teachers who are laid off to be first in line for new jobs. Principals would not be free to hire the best teachers they can find.
How does that serve students? It does not.
No, but the principal might have in-laws who are dying for work. But again: there are safeguards against that?
Best argument is FDR’s in 1937::"A strike of public employees is unthinkable and intolerable," echoing his predecessor Calvin Coolidge in 1919, when as governor of Massachusetts he broke the Boston police strike: "There is no right to strike against the public safety by anybody, anywhere, at any time,"
Not arguments, true, but statements of principle.