Ask supervisor *not* to come to viva? My viva is coming up, and one of my supervisors is planning to attend. I know that he won't be able to say anything during the viva itself, but I'm a little worried what he might say afterward while the examiners are discussing my fate. He's a good supervisor, and thinks very highly of my work, but he does have a tendency to agree with whomever he's speaking to at the moment. For example, if the examiners were discussing a small potential change to my thesis, I'm afraid his enthusiasm might get the better of him, and he might "volunteer" me to make a bigger change than the examiners expected or even suggest additional experiments which are beyond the scope of my PhD.

Does that scenario seem plausible, or am I worried over nothing? If there is reason to be concerned, I might ask my supervisor not to come, explaining that his presence might "make me more nervous" to avoid hurting his feelings.

If it helps, I'm in a small country which has an academic system very similar to the U.K. I have read Benefits to supervisor presence at viva in the UK?, but my question is a little different since I have a specific concern, and the supervisor in question has already invited himself.
In a UK viva, you are normally asked to leave the room when your examiners are deliberating your result. At this point your supervisor would also normally leave the room with you. As you said, they shouldn't say anything during the viva, and this should include any deliberation between your examiners. To be honest though, a supervisor does not want their student to fail, or have an unmanageable number of corrections, because that looks really bad on the supervisor as well. It's in their best interest for you to pass as easily as possible.

In the UK your supervisor is also never present without your permission. If your institution has these rules, then you can just ask them not to come. Just say that you feel it would add extra pressure that you could do without. It can be useful to have your supervisor there when you're read your corrections, as then they also know what you're asked to correct. In my viva I kind of got to argue potential changes during the viva, whilst we picked through my thesis. Since at this stage your supervisor definitely can't talk, you're in charge of your side of the negotiation.

Don't worry too much about changes. Your thesis only ever needs to be good enough to pass. It doesn't have to be brilliant, or better than anyone else's, it just has to demonstrate a significant contribution. You therefore shoudln't be asked to do more work for the sake of doing more. You should only have to change things if without them, your contribution isn't explained or supported well enough.

Remember that if your supervisor has supported your decision to submit your thesis, then there is little chance you'll fail. Try and enjoy yourself, you're unlikely ever to get to talk to two experienced researchers exclusively about your own work for such a long time ever again. Relish it!