If you cannot maintain your speed at the posted limit, and have no respect for when a U-Turn is allowed or appropriate, than you are not maintaining "superior control" of your vehicle. You're just trying to justify your asshattery. (Yes, we all got that you're talking about youself.)
Keeping your car at the posted speed limit has nothing to do with control or being an asshat. Don't tell me you never driven on a section of road where the speed limit is complete bullshit, and no other drivers pay attention to it. I remember a section a road where the posted limited was 40, but the traffic rarely went under 55. Driving the posted speed limit would have just created a dangerous situation for both me and the other drivers. Speed isn't necessarily the determining factor of how dangerous you're driving. It's your RELATIVE speed to the objects around you.
However, in some situations people making illegal turns piss me off to no end. If their illegal turn is causing people to wait unnecessarily, they totally deserve the "asshat" label.