Sims slyly manages to reference his opponent's age by claiming that he won't mention it (which, in effect, brings it up); this is a rhetorical device called
paralipsis.
Rotelle claims that Sims is too old to understand the issues, but instead of addressing the legitimacy of Rotelle's claim, Sims just shoots back, "Oh, yeah? Well, you're young." That may well be true, but Sims still needs to respond to Rotelle's allegation that his age impedes his ability to understand the country's issues.