Interesting response! From the way I see it, the two are intertwined (punishment and desirability). If the one is not there, e.g. punishment (as can be seen by my analogy), then the other must be the one that persuades the person, in this case, desirability.

I do not, however, act this way because of my selfish desire to be righteous, or good, or whatever we call it. Which was the initial point of my post against Glaucon’s conception of Justice.

Let me know if you disagree with this and if it’s more clear.