I really dont want to cause offence ! I lived with my mum with a lazy husband and two sons, my mum would comment to me about the things he was not doing etc and it would cause upset for me as I knew he was wrong but didnt know how to solve it as I was too busy trying to keep the peace between my mum and him rather than being left alone to sort it out in my own head what to do about it.

My advice is for you to leave things alone and let them get on with it as long as he is not affecting you directly (and not coming to the table does not count as you can ignore it) then leave well alone.