So? If Oh had control of those synths, she could have just had them all destroy themselves like F8 did. Or have them go rogue practically anywhere else in the galaxy except the place where your people’s salvation lies. The rescue fleet would then still have been usable to save the Romulan people.
Then if the admonition showed that, then as a member of the Zhat Vash I would seriously reevaluate my beliefs. What is gained for the Romulans when destroying synthetic life also condemns your own people to death?