And once again you ignore the fact that we're dealing with children as young as 11 and not adults. Since when has any problem caused by children gone away completely by simply by having adults tell them what to do? Expecting 11 year olds to act responsibly is a basic denial of what an 11 year old is. Sure the parent has to exercise some responsibility since their children can't, but expecting this problem to go away simply by telling children what they should and shouldn't do online is such a naive view of how parenting works that I'm amazed you can express it.
And that's if I even agree with you that you can't abuse even fairly innocuous sounding comments. Not to mention that you're also forgetting that you're also going to have to edit anything said before people knew their children would have their posts data mined. In the case of the older kids that's several years worth of posts that need to be edited or removed.
This isn't an issue that needs to be (or even can be) solved by the parents, except by getting themselves a less idiotic school board.
I was going to leave this be after the Lorric mess started, but after thinking about it for a while here I think it is worth responding to. Not because I think what you've said is necessarily wrong, but because it seems to reflect a significant difference of opinion.
You seem to be operating on the premise that these are young kids and therefore require careful handling because they know not what they do online. However, each and every single one of these social media sites have age of consent requirements, most of which are set at 13 (13 also happens to be 1 year after most democratic countries make kids criminally responsible for their actions). With parental consent.
I realize you are arguing pragmatically here - kids, like it or not, do not do what their parents tell them to and will create social media accounts, and really shouldn't be monitored by their school and experience social consequences for it. I, on the other hand, am arguing threefold: (1) young kids aren't actually legally allowed to have social media accounts without parental consent, (2) anyone who posts online should be fully prepared to experience social consequences of it, and (3) the social consequences really shouldn't be all that dire due to the nature of the information.
From a practical standpoint, if parents are not going to properly monitor their children online or offline, their children are going to readily feel the consequences of any unmonitored behaviour that crosses boundaries, be they social or criminal. Some people appear to think that consequences are right and just when these kids do stupid things offline, yet online behaviour should get a pass. I disagree. As I keep saying, anyone can collect this information this school board will be collecting it. Their peers will actually be a lot BETTER at collecting and using this information against a poster than will adults. The child is likely to experience more negative consequences from their posting behaviour at the hands of their peers than any school monitoring system. All of which goes back to the point that if parents leave their kids to their own devices, their kids are going to experience consequences of that. This isn't a bad thing - we accept it readily enough in the offline realm, yet somehow parents get absolved of responsibility when their children go online. Like it or not, until their child reaches age of majority, parents are responsible for the behaviour of their offspring - especially, I argue, their social media behaviour. And being a parent, that means I do everything in my means to make sure my little monsters don't get themselves in ****, whether or not I like having that responsibility. The "they're just kids" argument doesn't fly - kids have parents, parents are expected to obey the law (age of consent for social media) and be responsible for the actions of their kids. And if they don't, then their kids are going to experience the consequences of that, and ultimately the parents.
So, if a child feels the consequences of some inappropriate public posts, unless those consequences are themselves criminal or civil violations, they are precisely the fault of the party that put the information out there - the kid, and by legal extension, their parents - and that is as it should be. Just because they're kids doesn't mean they get a pass on the nastiness of the world in general, however unfortunate that reality may be. Better this lesson is learned in a relatively mild context than with life-altering consequences as an adult.
I don't agree with the school board policy, but I also very much disagree that this is not an issue that should or can be solved by parents. Parents have legal and moral responsibility for the actions of their children, regardless of how either party feels about that unfortunate reality. Which is precisely why both of my little troublemaking monsters will be given free reign of the Internet right until the time they **** it up and break my rules, as I monitor them without them knowing about it. The NSA has nothing on this father. Fortunately, I have a few years yet before I have to start worrying about it

None of this should be taken as agreement with the position Lorric is presently arguing, however. The policy should be shot down and shot down hard. School boards have much better things to be spending their budgets on.