It occurs to me that the NSA's behavior in this case is consistent with this being a situation like the DES s-boxes. If they designed Simon & Spec to be resista

It occurs to me that the NSA's behavior in this case is consistent with this being a situation like the DES s-boxes. If they designed Simon & Spec to be resistant to an attack that the open crypto community doesn't know about, they'd be really reluctant to talk about that design process or their internal cryptanalysis of them, for fear of giving away something about their secret attack(s). So Simon & Spec might be ok. Maybe.