Tough call. I happened to use a sidewalk today, but the adjacent road has no bike lane, nor hardly a shoulder even, and I was going to turn left into a shopping plaza, so I went down the sidewalk on the left side of the road, then into the plaza. However, I don't agree either with the casual use of sidewalks when there are suitable bike lane options; generally the peds are nearly as much trouble as cars. It might be something to ask the guy about if you get a chance, but it's probably not worth a shout-out. He may be very car-shy, and he wants that extra buffer.