Here's your hint, xerxes
$1:
mini grande
I wasn't into music that young, but I was in various music programs from elementary school to college... I was never "pushed" to do something I didn't want to do (for the most part) and therefore always had a good time with it. The times I felt like I "had" to do it were the least enjoyable, and the least productive. The director in college wanted me to switch majors to music, so it obviously worked for me.
I also don't know anything about this Sunbeams program, but is it a private lesson type of program? Kids at that age are going to want to do things with other kids, so trying to force them to practice when they don't want to is only going to hurt their impressions of music.
Let him take a break, if he wants it, and he'll come back to it, for sure.
Oh, and get his hands on some brass as soon as he's old enough... anyone can play piano