By your statement, literally every fight would end as soon as someone had a slightly superior position. That's patently not what happens. Being in a superior position to an equal or lesser skilled fighter means you are more likely to win, but certainly doesn't guarantee it, even then. Against a superior fighter from that positiion, it may not help much. Give me a BJJ above blue belt and let me get a superior position on the ground, and I've not yet gained a real advantage, because I'm in their area of strength (with a few exceptions of spots where I have skills that might balance things).You need to include what was asteriked at least if you want to quote it.
And you are, you should make no statement supporting the fact that you are not in a inferior position and you should have taken action to not be in that situation especially if you suspected somone of ill intent towards you. This can be applied to many situations, the one cited is the least worse one. (where you actually have a marginal chance, and that chance is not entirely based on the other person)
To support my statment, just replace "on your back" with "Being held up with a knife" or "being held up by a pistol/rifle". would you make any statement other than "you are done"? (now i will admit, there is a NOMINAL chance of besting the person in those sitations, but you have very little to no control, and this is if murder isnt the objective, you would have been shot or stabbed before you can think of a retort, potetionally muiltiple tiems if they are any good at it, again little to zero control, its their choice to shoot you and when, not yours.)
I also interpreted "on your back" to mean inferior positions in general, not soley on your back, but i already acknowledged being on your back is the least worse one i can think of. At least with what came to my head.