My take on this is if your supervisor has asked to sit in on viva, I suggest you agree. I know from your previous posts that you don't feel you've had adequate support, however, annoying your supervisor at this stage could cause problems if the outcome is anything greater than minor corrections. If this is the outcome, you will need to continue having a working relationship with your supervisor for at least six more months depending on University regulations and scale of corrections.
Also, if your supervisor has to submit a report and you've said no to your supervisor's presence, this could affect the nature of the report submitted. If a second viva is needed, the supervisor could if present provide pointers on how you could do better. Translated, keep the supervisor on side regardless of past working relationship. Play the system. ;-)
During viva, a supervisor is not supposed to play a part as others have said thus bar the report, is not supposed to be a direct influence. However, tell that to mine a few years back who during my bizarre viva basically wouldn't shut up!!!
Ian (Mackem_Beefy)