Joe should go into politics.
The shock of having an honest politician may be a bit much, but people would accept it. After all its "Honest Joe" after all. I have to admit, that I am assuming his superpower works over television, etc. and does not work only in his personal presence.
Joe is no longer accidentally using his superpower. He is using it intentionally to change the world for the better (hopefully).
As for his public policy speeches. He should be utterly dependent upon the teleprompter so that his words are carefully scripted to have the exact effect he desires.
In private he can instruct his advisors, etc. the tell me what you really think, don't worry about disagreeing with me. In fact he could get the best and brightest to advise him specifically about how to best use his superpower.
When caught in impromptu press contacts, etc. He could still control the message in acceptable ways. To dodge a question about current events, "I am not sure we know all of the relevant facts at this time but I am following the events and share your concern, next question place." or "I am not taking questions on that at this time" or "I don't have time to answer this right now" Best thing is, since even the reporters trust Joe, no controversial followup questions will trouble him.
Politics is about messaging. How do you say something to accentuate your message and not "step in it". Pick abortion as a an example, few things are more politically controversial in the US.
- As a Democrat: "I think abortion should be rare but legal. But ultimately at some level it is wrong to force a woman in what has to be a very personal decision."
- As a Republic: "I think abortion should only be legal in very restricted cases. Although I am very sympathetic to the women carrying an unwanted child, I cannot agree that killing an innocent baby is something a moral people can endorse."
I believe both of these statements are a pretty accurate representation of the party positions. Coming from Joe, both statements are perceived as reasonable by everybody.
Joe can memorize the stock phrases he needs to answer most questions to convey his precise intent. Deal with other question using his dodge phrases.
Now, if Joe is good and wise, we can have the best politician possible. If he is evil or foolish it could be very bad for his constituents.
If you have a superpower and don't use it you are simply wasting an opportunity. This waste will very likely eat at you as a failure of characters (if good) or failure to take advantage (if evil). Avoiding the power will cause Joe harm, and logically if Joe is good, harm others by not having the benefit of his beneficence.