CSF, the idiom is "behind closed doors." And many an American politician, on both the left and the right, has been put out of business by making a comment that he or she thought was "off the record." I think Jeb was indulging one of the broad prejudices that we all have but, he had the misfortune to have it reported.
By "broad prejudices that we all have," I don't mean that we all have the same prejudices. I mean that it's my belief that all of us think that the _ _[ fill in group name ]_ _ are _ _[ fill in negative adjective ]_ _. Mercifully, most of us are not put on record. And, CSF, I'm a flaming liberal that welcomes cultural diversity. But the fact is, humans form in groups and out groups and we love to snipe at the others -- e.g., Republicans (as opposed to conservatives) are stupid and heartless. It's true, but that doesn't mean it isn't prejudicial to hold those feelings.