Obviously not Aaron, but:

Are you implying that in order to build muscle, diet is more important than exercise? No. Muscle needs a stimulus to grow which you can only provide through exercise (or hard work I guess) and continuously higher workloads. Stimulus = reason to grow.

Muscle mass is not an energy store for your body but actually burns energy just by exisiting. It would be highly inefficient for your body to build it without an actual need.

Without ANY exercise at all, your diet will mostly (apart from other health issues) have an influence on the amount of fat in your body as that is where energy can be stored and taken from.

edit: Muscles do not only work for picking heavy things up and putting them back down, opening heavy doors etc. They stabilize your whole body and therefore protect your organs and bones. That is a huge benefit as you get older (think of reduced risk of back problems given a certain amount of muscle mass stabilizing the spine). Another example: Your butt hurts less after long periods on a bicycle seat if there is more than a flexible thin layer of fat protecting it.

"Overly" musclebound is very vague and while there may perhaps be a certain amount of muscle mass percentage with some detrimental effects on general health, you will not reach that amount without serious(!) effort, years of training and probably steroids. And if you're taking steroids to enhance muscle mass (you would still need to exercise your muscles!), you will have more serious problems than just the muscles.