First of all, the winning school's headmaster issued a public apology for the lob-sided victory. When the coach publicly disagreed with the headmaster, he got fired. Any good boss, CEO or president would have done the same. If the coach had kept his mouth shut, he would still have his job.
Second, this is a private school which depends on good PR for enrollment. The headmaster was looking out for the image of his school.
Third, being a Christian school, they don't need a win at all costs coach in any of their programs, unless they are playing a private muslim school. In this case, they were not.
Frankly the school board chair should be fired for attacking his own students. The coach did the right thing and stood up for his girls. He’ll get hired soon I bet. Hopefully by a school that can appreciate him