I think the best way would be to fetch the operator id from the client registry when the player object is created. The down side is that we create yet another dependency to client registry, which is not really supposed to be used in the game nodes, but that might be ok. The other issue is that we cannot be 100% certain that we have a session in the client registry and thus an operator id. It seems reasonable that if we get a request to join a table/register for a tournament that we have a session though.
Important: For tournaments we need to fetch and store the operator id when a player registers for the tournament and not when the tournament starts.