Why?
Because they've violated the Geneva Conventions. So they are asking Congress to say to add an "except when not" exception to the War Crimes act of 1996, which criminalized violation of the Geneva Conventions (as well as justified our insistence that the US is not subject to the International War Crimes tribunal).
So Alberto has been pinging Republican members of congress to carve an exception for recent behavior. It seems the Administration might now believe that their violating the Geneva Conventions might not actually be covered under the President's war-powers act -- I dunno, maybe because the Supreme Court says it's not.
So how about no? How about, if members of this administration committed a war crime, they be convicted of that in American Courts. The War Crimes Act reads pretty well to me, and I don't think there's any good reason to make it easier to, say, I dunno, kill someone in US Custody.