Have a great time on the Star. We took that cruise in November. Let your son bring his guitar. It can be a real ice breaker. In the later evenings there is nothing going on on deck, unless it is one of the nights they are throwing a party out there, It would be a great place to strum his guitar. There is a large area in front of the pool that has layers of lounge chair that is deserted at night. And last but not least there is the talent show. If he is good he may want to sign up for that. ( Oh heck even if he isn't this is a great opportunity to step out take a risk and go for it. He'll never see these people again and it will be a fantastic experience for him.
As they say JUST DO IT,
Do the canopy tour in pv also.