I am not sure what college counselors say. We never used one.
I do know what at least some people who actually attended “top 10” universities say. At least the people that I know who attended “top 10” universities agree with the general theme of the “applying sideways” blog that @tsbna44 referenced above. As I understand it, it recommends that you do what is right for you, do it well, and treat people well. Of course very strong academics is assumed for anyone applying to a highly ranked college or university.
To me it sounds like your son is doing what he feels is right for him.
It is hard to be at the “top of the game” in two or three ECs, plus classes. There is some limit for each of us.
One daughter was like your son a very good musician. Eventually she needed to neglect her music to focus on other issues, such as academics. This happens. We each need to prioritize. I expect that the music will probably come back, but it has been a while.
I think that your son should keep doing what is right for him. In a similar situation I would be very open to having a child drop back to doing slightly fewer things if they felt that they need to do so. Otherwise I would not worry about it.
The other thing that comes to mind is that there are a lot of very good colleges and universities. I would not focus on “Top 10” schools, but rather on finding schools that are a good fit for the student.