As for the reason why Hersh did this, I cannot say, a person's intention is a black box. But this kind of behavior amounts to some amount of dishonesty. It's not much more complicated than that.
Is saying he misspoke. His words were interpreted in a way he did not intend them to be.
Addressing only the quote itself is unfair, as again that does not represent his actual argument.
I'm done with this.