That makes absolutely no sense whatsoever. Humans are named by their parents, not their superiors.
It isn't the character naming the captain, but the player. It'd be useful for continuity and roleplay purposes, purely.
Edit: To clarify...
Let's say I recruit a unit of men with a captain named John. I create RP around the interaction between captain and knight, insofar as there is interaction, and this becomes a core of my roleplay. The unit is left to become a militia unit, but my knight would probably drag the captain along after him in his retinue when recruiting a new unit as the militia unit would be staffed by administrators native to the region it's in (and not mercenaries or foreigners, or whatever.) I recruit a new unit, but this captain is named Ted. Suddenly I need to explain away where John has gone, and then after that, explain away Ted too when I get captain Timmy.
I'd just like the ability to alter a NPC captain's name so that Ted could be John - I could play it as the same man, etc., assuming he has survived that long.
Alternatively, let's say my character is playing in a realm where Viking names are commonplace. Suddenly a captain shows up to lead my unit of murdering, baby-eating marines and his name is 'François' - where the hell did this Frenchman come from? It doesn't fit the theme of things, and there comes a time when "mercenary captain" starts to sound tired and overused.
