For someone with a schedule as heavy as Romney's (or any major politician), I imagine you shoot when you can get a chance. If high sun is when he's available, that's what you work with. Besides, it's a political ad, not a touching, highly personal cinematic portrait. Five seconds in Photoshop would have made that mic go away, though.
That may be true, but a professional DP would throw up a scrim over the subject or some netting. Heck, I've done this for "person on the street" interviews. It takes all of five minutes to do it. This, with the lapel mic screams "amateur hour."