If this was a case of libel against a person, asking for proof (thus source) would still be sketchy, but understandable (the sources are not the primary goal of the discovery, truthfulness of the reporting is).
This is _not_ the case. This is clearly an overreach, and if this was in Europe, I would have helped ngo to present the case in front of the ECHR, as this seems like a human right violation. Do you have an equivalent in the US?
The USA executes people with impunity anywhere in the world. It has secret torture cells where people disappear or just die. Internally, it jails people for wrong think, manufactures terrorist threats, forces businesses to filter and send data to allow sweeping surveillance. It then spreads democracy by conducting coup operations, selling drugs, fixing elections, or if none of that works, plain old bombs work fine. At the same time running the most sophisticated propaganda campaigns in the world with the full support of almost everyone who reads this website.
Why would you imagine that this system would have justice or functioning courts?
https://thehill.com/opinion/campaign/4481433-cbs-faces-uproa...