I'd probably ask that, if the Rat Pack theme didn't pan out for him financially after whatever time frame he is willing to lose money over, that you be allowed to play that period of time doing what YOU think the audience wants, and see if it can be rescued.

Otherwise, I'd be cautious... There are many restaurant owners that think that whatever harebrained scheme they come up with is, of course, brilliant, and the only reason it didn't work was the poor musician forced to abide by it..!