According to my theoretical possibility generator....
In the likely event of Sonic having to face Mecha-Sal, it would possibly cause emotional trauma to the latter hedgehog if the doctor were to give Mecha-sally a voice. Being that they are in relationship terms, it would be purely sadistic torture to hear your girlfriend actually cry out in pain as you fight her roboticized self. If I were the Doctor, I would do so, and it would ultimately break Sonic's sanity and Will to live, and eventually, he would be done for, and have such a low outlook on life and disappear forever, allowing Robotnik to successfully single out and Roboticize the other Freedom fighters and finally take over Mobius, and leave a sad, pathetic, depressed and hopeless Hedgehog to his own demise.
Wow, that would be quite a sad and intense story you thought up there.
Although, wasn't the latest attempt at the roboticizer destroyed by Sally when she had the beam invert itself?
I think Snively even made a comment saying it was not just offline, it was gone.
That does raise another interesting question.
Why did Eggman need resort to, "restarting Mobius" in order to roboticize again?
I mean, there was no reference that the current roboticizer before that was destroyed.
All it said was that everyone was deroboticized now. Well, except for Jules and Bunnie of course.