I'm only guessing here, but I assume the comments on Residential schools are there to establish the bigotry of the board.

The actual flag ban is typically done to prevent pride flags from being on display.

It's about a racist group of people, who are currently under a provincial advisory board, but decided to have an official meeting without the quorum of individuals needed to have an official meeting.

What they passed is incidental to the story.

There are some linked articles that provided more information. The superintendent was fired days before a pride parade that was promoted by the division and the MMF. There are a number of conflicting claims surrounding his dismissal, which will probably get ironed out in court. The usual reason for banning flags is the suppress the promotion of something you don't like, otherwise taste and relevance would be sufficient. Someone needs to start finding perfectly legitimate flags to be flown that don't meet their criteria, such as city flags, sister city flags, flags for Saskatchewan in towns near the border, etc., until the rule is made to look completely absurd or they say out loud exactly what they are bigoted against. If nothing else, it will tie them up dealing with inane topics so they don't have as much time to do more harmful things.

My guess, based on the related articles, is that they want to ban the MMF and/or pride flags.