Well, 8th grade is a bit early to decide if a boy is a good singer or not! My son started choir in 8th grade. His voice was changing. He surprised us all and made all state choir in 9th grade.
Let your son take chorus. If there’s built-in community and a great teacher it’s all good. It may turn out to be a really fantastic experience, not to mention all the skills learned by being in a music ensemble. All my kids did music, art, theatre in high school, multiple electives every year, and it has often been tough to work in the academic stuff around every possible music class. They did explore other interests as well, along the way. My youngest is a senior (and the only one pursuing a career in music). Not a single regret. It was not a problem for college admissions. If anything it was a positive.