Sad news. Glad he wasn't hurt too bad and hope he makes a quick recovery!
As for sidewalks, yeah... I figured it wasn't the safest place to ride even before I found this site and then I read all the posts here and vowed to ride sidewalks as little as humanly possible. (I seem to remember a close call or two with cars backing out of driveways when I was riding in my neighborhood growing up that probably gave me a practial understanding of the dangers.)
I've come to notice that since I began commuting and riding regularly, I conciously stay on the lookout for sidewalk riders, but mostly b/c I read so many stories here. I'm trying to be more careful when behind the wheel, but it's obvious from this story that not everyone is (oh, and BTW, the sky is blue).