Does he not want to listen to MOH or is it that when he puts people on hold they don't hear MOH?
I'm thinking that if he doesn't want to hear MOH you may be removing it from the system.
But there may be a way to accomplish it. Put him in his own tenant and allow access to all trunks and extensions in your primary tenant.
I'm still pretty sure though, that he'll still hear it if someone puts him on hold.
Or, perhaps, never tried this, it just occurs to me as I write this, that perhaps if you put the MOH port in an interconnect restriction that is blocked from him, that might also do it.
Ralph