I'm all for multitasking, but let's face it, when you read and walk you do neither well. Read. Walk. Read. Walk.
Why would you even read and walk? Like, is your book just so good you can't put it down? Is this some kind of ill-concieved time saving strategy? Or do you find your surroundings so unbearable that you need to escape into a book? I'm not sure you can actually read effectively while walking anyways. Why not walk somewhere really fast, get there early, and read for a few? It's clear by the meandering start-stop pace of a read walker they are literally experiencing the worst of both worlds. In any case, I hope the climax to the last Harry Potter book involves you getting hit by a bus.