I certainly am assuming that the throat-striker is inferior in this situation. Why? Because you said this dude has 'the baddest overhand in the land.' For his technique to be so much more developed than everyone elses, he'd pretty much have to be a high level competitor.
Though you can definitely prepare for both, self defense and combat sports are different paths. Someone who's really good at one, doesn't tend to be as good at the other. Putting in the work into each field will yield different results. A high level combat sportsman will be an EXCELLENT fighter, and will be able to overcome most people in the world in a 1-on-1 fight. This includes the high level self defense practitioner. However, the self defense guy could survive many situations that the combat sportsman would get killed in. Combat sports gets you good at fighting, self defense arts get you good at surviving bad situations.
So, unless I misread your meaning, I'm assuming that the guy with the overhand right is a high level competitor. The throat-striker is almost certainly not as good a FIGHTER (though he may be equipped to handle many more self defense scenarios).
That's my thought process on this...
Plus, when you were saying things like 'a 60 year old lady could collapse someone's throat with a strike,' it seems like you're saying that dirty moves can overcome superior skill (when you consider 'the baddest overhand in the land' example in conjunction with this).
I can see where you're coming from with competitior vs survivalist. But I think that in this situation, one where there are no rules, a survival situation, the survivalist has the advantage.
Which was my meaning with the original post on page 1. In the cage, a pure Kung Fu fighter, Karateka, Judoka, anyone not well rounded would get smacked around like a redheaded stepchild, almost no question. However in a street situation, I stand by my belief that a competition fighter, conditioned for competition (rules, limiting techniques, etc), will not be as prepared for a survival situation (now my favorite description for a no-escape situation!) in the manner a self-defense fighter would be.
In that way, I suspect a fighter who'd totally conditioned himself to strike at vital points, to damage his opponent's body to break his will so as not to die, would be able to apply the proper counter to any competition fighter's overhand.
The term regarding the elderly woman was in regard to the resiliancy of the human biology against this technique when properly performed. I have no belief that grammy can kill an MMA fighter.