willow, i think that as the loving and caring big sister that you are, you should do everything you can to promote and assist your brother in his chosen career. which means not throwing him out of the kitchen, but helping him practice the first job he will have when he leaves that prestigious cooking school - prep cook. meaning he gets to a whole lot of scut work. guess who peels the potatos? the prep cook. guess who does the cleaning and prepping of veggies for cooking? the prep cook. guess who gets to help the dishwasher when every stinking pan in the kitchen is dirty, the dishwasher is behind, and the kitchen is slammed? the prep cook. guess who gets to do every single menial job that no one else has time for, or wants to do? the prep cook! after all, it's only fair that you help him out if you love him!!!
you might also tell him, when he demands a $45 piece of steak that if he spends that much money when he opens Chez Brett, he'll go broke in six months! he obviously hasn't been paying much attention in food costs class!
my future son-in-law is a chef. he graduated from a prestigious cooking school as well. and over the years i have watched his ability to turn ordinary ingredients into simply wonderful food, and his ability to work "clean" to be amazing. does he splurge on expensive ingredients sometimes? sure. but as his career has progressed, his skills have developed along those lines. he is now the sous chef in one location of a Washington DC based chain with an excellent reputation, a chain that routinely makes the "Best" list of local restaraunts. he didn't get hired by telling the chef what kind of meat he expected to work with.
an excellent book for Brett might be "The Soul of a Chef" by Michael Ruhlman. especially part two, which details the story of Michael Symon of Cleveland. when that book was written, Symon was dedicated to the idea of having no entree on his menu that cost the customer more than $20 or $25 (i can't remember which). to profit (and profit he did), Symon had to be vigilant about food costs. he is also a graduate of the CIA. it doesn't get much more prestigious than that.