I'm sure that Phil Robertson has gotten a lot of PR support over the years. I've seen it happen over and over again though: someone gets used to receiving only positive coverage and gets overly confident about press interviews, and then refuses formal media training. Amazingly, things can go great for years... until that one disastrous interview where everything changes. Then every interview after that focuses on that issue for the next few years. Then a PR team gets called into manage the newly formed crisis situation.
That's probably what happened here: he had gotten used to getting tons of positive coverage, and he started to think that he had a handle on the press. So he (and his team) start to do less and less preparation and due diligence for each interview, until this disaster occurred.