What he said. Rank is no excuse to be a dick.
What he said, and the He before him. Rank is all the more reason Not to be a dick. The dickiness is a sign of self importance and that is the result of an un-checked Ego. Or even a bunch of unchecked egos that run the power/etiquette enforcement of a dojo. Like in a petri dish, the self-importance phenomena can spread in a dojo and you may not find support from 'upper management'. But I would ask you to take the advice of David Skaggs and look for another dojo to train at for a bit, just to get a reality check on your personal situation. And I am inspired to remind you that Sempai are there to provide real examples of the benefits of training through their behaviour in all aspects of human relations within the dojo (and arguabley, without) as well as help you responsibley understand the rules. If they have left you feeling drug-out, well....
And finally, I would recommend reading the rules of etiquette from the Aikido Schools of Ueshiba.They are comprehensive and address all members of training life, including sempai and sensei.