I guess times change, in my C5, I did not get any factory plug kit, just the runflats. Those were replaced with GS-D3s and my own plug kit and small compressor. And I agree, plugs usually void the warranty (as well as the speed rating), but I believe a professionally installed plug/patch is ok...I think. And plugging the sidewall is not advised, but if the tire is destroyed, you are in a desert, and it will get you to a paved road (AAA requirement), it works!
Someone with the knowledge might answer on if a plug/patch will keep a tire warranty.