I think that many are hyper-sensitive to cyclists they {assume} to be drafting, they then do something stupid as retalliation, risking an accident that might not have otherwise occurred. If you're unable to ride them off your wheel then, what's the harm, really? Once I've ridden over that section of pavement or, used that air, I don't what the next guy does with it. Remember, it's the guy in the back that's at much greater risk of crashing when wheels rub anyway. So, if he's too close and inexperienced, the problem may just take care of itself. Just ride and stop worrying about what everyone else is doing.