My spoiled babies get to go out on the deck whenever they want when we’re home, I even planted kittie grass for them, they have a kittie door into our garage, that’s where you’ll find all 3 of them most of the time, I was looking into the cat wheel, they’re kinda pricey, especially if they don’t use it, like all the other cat toys we have, they rather play with tie straps, string, finger nail files, etc... they do like their wands though.Could be he is just trying to be alpha and still picks up the scent from Echo's accident, anti icky poo is the best for scent removal, hopefully that works.
If it does turn out to be a behavioural issue, u might try finding him a energy outlet, cat wheel or if u have a patio turn it into a catio so he can go out before his walks maybe even put a litter box out there for him add a kitty door u can lock and unlock so he can go to the catio when he wants while your home.
Pics of Echo and his sis to please.