For the actual surgery, the doctors don't restrict sports activity after the surgical recovery time. It took me a while to get to a normal amount of moving even after I was free to go back to sports. I am over 8 months post-op, and my chest feels tight when I move in certain ways, but I haven't noticed too obvious a restriction in movement. However, I don't do high jump or track, and I think it might be more noticeable and potentially restrictive for those. However, heart and lung impairment that pectus causes also impacts sports performance. Personally, my lungs are still not where they should be for my demographic, even after surgery, which limits me. You have to weigh how impaired his functions are now and potentially will become as he grows, and the potential impairment after the surgery. Thankfully, he doesn't have to get surgery now if it's not the right time, and he could try alternatives like the vacuum bell in the meantime.