What really fucks me isn't just the lie, it's that the lie is a defense by admission of incompetence. Either he did sign and is lying to the government and everyone under oath, or he is not lying and he is admitting he is so incompetent at his job he would sign off on anything put in front of him.
If anything, that should be the gotcha here. "So your defense for this action of labeling parents in the same terms as criminal rioter is that you are too incompetent to be expected to read the things you sign Mr. Garland? Should we be worried about you accidentally dropping charges on someone on behalf of the US government or leaking classified information because you signed a memo without reading it then?"