There is more teaching in that example than spending 15 minutes abusing your partner. All you teach him/her with the latter is that it's ok to physically act out when angered.
I disagree. I think you teach the individual that it's not wise to say stupid things that deliberately provoke a fallible human being. In the future, this lesson could prevent this individual -- who clearly was suffering from considerable arrogance -- from making this mistake with someone who did not exercise any restraint.
You've characterized the response as "15 minutes abusing your partner", and that's met with general consensus in this thread. I don't agree with the response, and yet I think we should remember that the response was
modulated -- not as much as you or I or many people might have liked, sure, but it was also not an act of uncontrolled anger and aggression. Had it been, it would have ended much sooner than 15 minutes, and uke would have gone to the hospital. Instead uke took 15 minutes of ukemi that was more rigorous than he would have liked. I'm not making an "at least he didn't break the guy's neck" argument here. I'm just saying that some of your statements have drifted into the absolute, and that's not supported by what we know of this situation, and maybe a bit of perspective is needed.