The main reason the parents are not suing, is they can't afford it. Justice is a luxury for the wealthy. What needs to happen, is either the interested media networks or support groups with a special interest in this, need to financially support this fight.
There were times I wanted to sue the local school for their failure to protect difficult child 3 against the bullying, and especially for the times they reinvented the truth merely to avoid having to deal with these serious issues. But even though to me it seems so obvious, I know how well they muddied the waters, plus time has passed, plus I would not have any witnesses or supporters if I tried, because the town has been so thoroughly cowed by the bullying tactics. It would revisit a lot of stuff we have moved on from.
But that is us. My method of dealing with this has been to fight them for legal rights and to fight for more services according to the law. We don't have individual districts here that can sue - the Dept of Ed is state-based and government controlled. If they tried a lawsuit like this, the government would have to step in and prevent because it would be unlawful.
It sounds to me that in this case there is one important, vengeful official who is determined to drive this family out of the country. I would suggest the TV network find out who it is and do an expose. All's fair in love and war, and this is definitely war.
Marg