>>660425>>660445There are literally no circumstances under which engine or transmission oil would enter the brake system, and pondering what would happen if this took place is pointless.
Now water is a pretty common brake fluid contaminant, so common there are special sensors designed to test water content in potentially contaminated brake fluid. Though only when 1/20th of the total fluid is water, is this universally recognized as a hazard. Even then, brakes still function under normal driving conditions, albiet with a bit of a spongey feel. The real danger comes after prolonged drives, when brake hardware heats up. This can cause the water in your brake lines to boil and create air pockets. Even in this situation, the emergency brake is cable actuated and can still be applied.
Really you'd be much better off hoping he gets prostate cancer.