She was still pefectly free to be critical of Israel.
she refused to sign an oath vowing that she “does not” and “will not” engage in a boycott of Israel or “otherwise tak[e] any action that is intended to inflict economic harm” on that foreign nation.
As a gov’t employee she’s absolutely bound to follow the laws of the state and anti discrimination laws are completely constitutional.
She was however contractually bound to a higher standard as are all teachers. If their actions put the school district in an indefensible position with respect to discrimination they have to be gone.