Am I missing something? Fox didn't conduct the survey, and it wasn't a survey of their viewers. The survey was 1,006 Registered Voters. Not saying this survey is legit, because I don't know enough about Anderson Robbins Research or Shaw Research Company to form an opinion.
Now as far as my opinion on this survey, I am not surprised. The survey took place June 1-3, firmly in the middle of the Bowe Bergdahl issue. Emotions were running high and I'd guess this survey represents emotional responses. His foreign policy approval dropped 5% from the previous poll, it's not rocket science to figure out why. 5% is a huge number, considering how few people are actually open to changing their mind on the President in either direction. I'd guess his ratings go back up once people in settle down. In that sense, I would say this survey is fairly irrelevant.