(Side question here, but Goto was programmed to serve the republic, even if it meant breaking its laws due to a programming conflict at a point, but does that programming still exist? If it did, Plaegius could make himself seem like he would bring it back and he was its only hope for resurrection, thus making Goto completely unable to harm him, and making it an almost-auto win for Plaegius. I say almost cause we all know how much those HK-50s enjoy killing organics.)
No, that wouldn't be allowed as that technically counts as surrender on G0-T0s part. But in a real fight it would be possible so let's just consider it. IMO this would not work, G0-T0 knows Plagueis is Sith and he sees both Sith ans Jedi as negative for the Republic, so he would seek to destroy him. He may see Hego Damask as good for the Republic but when he discovers his true identity he will will not. And even if Plagueis does attempt to convince him it will not work, because as a Sith G0-T0 will see him as inherently bad for the Republic due to the countless wars the Sith have waged against it.