Yes you can get closer, but I didn't suggest it, because he already looks like he was standing a nice distance away. Too much closer risks making the people look disproportional (if you imagine the extreme example of using a 10mm lens an inch from somebody's face, their nose would be 5x bigger than their ears. Same thing happens to a lesser degree when moving from 20 ft back to 5 ft to get shallower DOF). If a wider aperture is available, I think that's a safer route. If not, by all means move closer, it won't be the end of the world.