Hopefully a simple check would have also shown that he had custody of his kids and therefore the right to pick them up at school.
Having worked for a school district for 30 years, I know for a fact that sometimes non-custodial parents show up at school to literally kidnap their kids. I am not saying this was the case here, but unless you have experience with some of the crazy stuff parents do with regards to their kids, you can't know why school districts feel they have to take every precaution on behalf of the kids. If he had been a non-custodial parent and the school gave his kids to him, the school employees who allowed this and the school district would be open to a winnable lawsuit.
So let me get this straight. You defend the parents not being given their children back in case one of them is kidnapping their own child?
You do realize that the schools know who the legal guardians of the kids are, right? It's sort of a requirement of having kids in school - telling the school who the guardians are.
Without that they'd have no idea who to give the kids to anyway.
Weak defense of outrageous behavior....