Brutus isn't much of a family pet, but then as Rottweiler at 130 pounds, he was never destined to be one. While he is friendly enough with those he knows as long as his pack leader (that's you) is in the area, his real job is as a guard dog As for grooming, well, let's just say it is not really his idea of a good time. Fortunately, Rotties are low maintenance dogs, but the same steps apply to long-hair breeds. The big difference is that with longer hair you may have to spend more time working through tangles and mats.
From Brutus' point of view, half the reason he doesn’t care to be groomed is that he simply doesn't like being touched all over, it sort of goes against the whole guard dog image. The other is that the tools you plan to use make him just a little bit more than nervous. Take your time and work with Brutus, letting him overcome his anxieties and fears at his own paces. Consistency and patience are the keys to success!
Just because Brutus' main job is to guard and protect your home and family when you are away, it doesn't put him in the Alpha role at any time. The more time you spend working with your pup, the more he will come to understand the grooming process, as well as the chain of command, and will come to look forward to it.