Who's this MU Georgiou that you speak of? The woman working for Section 31 is retired Starfleet captain Philippa Georgiou formerly of the USS Shenzhou, currently working as a independent Starfleet security contractor. Just ask her. And the Romulans would have no reason to believe otherwise.As leverage to force the signing of the treaty by the “goody two shoes” Federation, all the Romulans would need to do is threaten to reveal MU Georgiou to the public. Just an example of potential blackmail material.