I just posted an excerpt from something Joshua said in Episode 302 about pleasure ethics from Thomas Moore's Utopia, and another quote comes to mind which is on a related topic and which responds to Cicero's allegation that an Epicurean should not boast about doing everything for his own benefit. (That were it ever so true, that a wise man regards nothing but the body; or, to express myself with more decency, never does anything except what is expedient, and views all things with exclusive reference to his own advantage; as such things are not very commendable, they should confine them to their own breasts, and leave off talking with that parade of them.)
A part of what I would include in responding to that would be to point out how much emphasis Epicurus places on friendship, and placing the interest of our friends as important to us as our own. As Torquatus said about his ancestor, we are strongly motivated to do unpleasant things for the safety and benefit of our friends country as that is our own strongest assurance of safety. I would suggest that this kind of wider concern equates at least roughly with one's friends, at least for someone in public office in the sense of Friends, Romans, countrymen, lend me your ears....
The quote that comes to mind to support the view that this kind of concern for our friends is natural, and would be fully sufficient for someone to proclaim to the public, even on taking an office as to the principle on which he would act while in office, is the following from Nietzsche which I've cited before, from The Gay Science. Nietzsche doesn't seem entirely happy about it, but he's making a point I think most of us can very much appreciate:
QuoteHow is it possible to keep to one’s own way? Constantly, some clamor or other calls us aside; rarely does our eye behold anything that does not require us to drop our own preoccupation instantly to help. I know, there are a hundred decent and praiseworthy ways of losing my own way, and they are truly highly “moral”! Indeed, those who now preach the morality of pity even take the view that precisely this and only this is moral—to lose one’s own way in order to come to the assistance of a neighbor. I know just as certainly that I only need to expose myself to the sight of some genuine distress and I am lost. And if a suffering friend said to me, “Look, I am about to die; please promise to die with me,” I should promise it; and the sight of a small mountain tribe fighting for its liberty would persuade me to offer it my hand and my life . . . All such arousing of pity and calling for help is secretly seductive, for our “own way” is too hard and demanding and too remote from the love and gratitude of others, and we do not really mind escaping from it . . . while I shall keep silent [verschweigen, i.e., hide, conceal, keep secret] about some points, I do not want to remain silent about my morality which says to me: Live in seclusion [Lebe im Verborgenen, i.e, live secretly, discreetly, in hiding or concealment] so that you can live for yourself. Live in ignorance about what seems most important to your age. Between yourself and today lay the skin of at least three centuries. And the clamor of today, the noise of wars and revolutions should be a mere murmur for you. You will also wish to help – but only those whose distress you understand entirely because they share with you one suffering and one hope – your friends – and only in the manner in which you help yourself."
(GS 338)[37]
(the source from which I originally got this quote appears gone, but i see this link on archive.org.)
So I would argue that Nietzsche is pointing out something that is very natural: that we want to help the people we consider to be our friends, and we are often motivated to do that with more enthusiasm than when we act for our own sake.
I might also combine this with an allusion to the common idea that if we were marooned on an island or another planet with no company at all we would soon either go crazy or lose the will to live or both - sort of how we might feel if we were the only survivor of a nuclear war.
So there are lots of ways to stand up in public and say that because you in fact value your own interest, and that you identify your own happiness with that of your friends, just as Epicurus advised, you are not only as trustworthy as anyone else, you are more trustworthy because you place your actions on a strong practical foundation and not on a make-believe supernatural god or ideal morality.