Not really. It's just that intervening in child abuse is one of those proper roles of (state) government.
What you are arguing is that we should be willing to trust government outside of the carefully crafted chains forged for it by the Founders. I am not willing to so do.
The Founders left the States with broad discretion. Reviewing a parent's curriculum plan to enusre that parents who are taking their kids out of school are actually educating them, and not using it as a cover for allegations of abuse, is well within those bounds. Could it be abused? Probably. Should it therefore be rejected? Absolutely not - not when the possibility of abuse is weighed against the compelling interest the State has in ensuring educated citizens who are not abused, and in light of the minimal intrusion into the parent's privacy.
It should be noted that the slippery slope argument can be a logical fallacy.
THEE: "and in light of the minimal intrusion into the parent's privacy."
ME: I hope you are making a joke. Given the large, and growing number of cases of AgencyAbusers acting out, all across America, you must be jesting.