Unless we want to be Orwellian, shouldn't we assume good parenting?
I don't know what the word "Orwellian" has to do with this. Then again, I find it quite overused and misapplied in general.
Whether we should assume good parenting seems to me highly dependent on the issue in question, the country or state, and the individual child, among other variables. So, for example, if a school told a father in a particularly conservative part of Saudi Arabia that his child needed to spend more time with parents, I think it would be quite reasonable to assume by default that the father would respond well and in the child's best interests. But keep everything the same and change "needs to spend time with parents" to "the child is homosexual [or an atheist]" and the result would most likely be disastrous, and in most cases, I think the default assumption about those two specific subjects should be immense caution with parents in Saudi Arabia.
I see no universal answer here. It depends on context.