it seems the overall group behavior on american roads nearly dictates rudeness from a majority of road users regardless of mode of travel. such it is. there's a lot of waves and smiles too, don't get me wrong, but wether driving a car, bike or walking, i get the general impression from other road users of disregard of all others in pursuit of ones one expediency.
I don't see why the bicyclists should be expected to act any better than the motorists.