Advise on dealing with rats on different trust levels

Hi all. I have two young boys. One of which (Arthur) is really well behaved and I totally trust him to have completely free roam of my flat when it is play time. Sadly, my other boy (Patrick) needs constant supervision as he will try to bite everything and hide under furniture. Sometimes, I can tell that Arthur is desperate to come out but I know that I do not have the time at that moment to supervise Patrick so I end up not letting either of them out until later.

Is this the right thing to do? Or could I let Arthur out while Patrick is still in their cage? I obviously will still give both of them the right amount of play time, but is it bad to give one some play time without the other?