Re: dojo frat boys
Who's teaching the other 65% of the classes? Any use talking to those instructors? The frat boys would be easier to take if you also had some classes that focused on your needs. Maybe you could try to rope off one class a night for the mid-ranked people--all that would take is one sympathetic instructor. (Don't overlook high kyu-ranked teachers, either. I've learned a lot from mine.)
Failing that, and if you're otherwise motivated to stay at this dojo, I'd try to form a good training group out of the people who do work with you, and write the frat boys off. If you can make strong connections with your usual partners you can learn a lot and have a good time, even if you aren't getting as much teacher attention as you'd like. Are there older or female yudansha who aren't part of the clique?
Finally, if you can do it (I have no idea of your dojo politics) you could consider trying to set up a seminar with a female or older instructor. Having a vivid demonstration that not all good aikidoka are arrogant young men sometimes helps. I've read a couple of accounts from ex-arrogant young men who said that being partnered with very skilled older people opened their eyes in a big way.
I'd take somewhat seriously the advice to look for another dojo, too. I wouldn't if it were just annoying students, but having the head instructor being hostile to suggestions is worrisome. And I've been lucky enough not to see the pattern you describe in any of the four dojo where I've trained, so you've got decent odds of finding that things are better if you go elsewhere.