I think you may be trying to push the slippery slope argument. And I agree, except against what you're probably thinking.
This is more about making sure these idiots don't block traffic for no good reason.
Take the lane if you have to, hell stay in the lane if you can't move over (I usually point out bad road conditions so drivers know the reason why I'm blocking the one and only lane of traffic for an extended period of time), but for the love of god don't block the whole road and make every vehicle wait behind you at 15mph.
Hell I'd be pissed too if I were on my BIKE and a bunch of idiots decided to go 15mph and block the entire road.