With all this talk of a beast and how you should never let it out to play doesnt this set you up for misery and depression if you never have ANY fun? Sounds alot like the ascetic priests/mendicants.
To me it seems pretty simple- accept that your body has primal urges and since it isnt able to reason and you are dont let it follow stupid urges that get you into trouble but instead let it have its 'feasting' on healthy pastimes.
A dog might be naughty if you let it and especially if you don't let it out for walks and to play. So it doesnt act up its important to give it attention on YOUR terms. I think this explanation is better than the me vs it dichotomy.
I doubt trimpey talks about it much from what I gather so far but that is how I'd put it. You have to have SOME fun in life and not deny any part of your being. I think its more about integrating even your beast and letting it have its fun with more healthy pursuits.
Trimpey has given me a nice new paradigm to work with but I feel it can be refined somewhat.