Does singing voice matter on sax?

by Mommy
(Phila, PA)

I love music but am technically a musical ignoramus. My 13 y/o son was appalled at my ignorance when I told him, basically, that an alto sax should be played by one who sings alto, soprano by a soprano etc., so when his voice changes he may want a different sax. So we should wait before purchasing his instrument.
Even as I said it I kind of felt like an idiot. But is there anything remotely sensible about what I said?
Thanks in advance for any advice you've got.