I think it's a good idea (the muppet). When my nephew was very little, at Christmas time my SIL got a name off the Angel tree at church. One Sunday she brought the presents along to Mass so she could drop them off. Nephew asked what it was all about and SIL explained it was presents for poor children who's parents couldn't afford to get them anything. Nephew then asked "So if we give them the presents, they won't be poor anymore?". My DB and SIL are great parents who do their best to let their kids know how lucky they are, but with pre-school aged kids it's often hard to relate. Having a character on SS is a great way for kids to "see" it better.
Not to mention, a lot of parents watch TV with their kids so it's a great reminder to the parents, too!