It is good that you and your son got this experience early on. The brackets don't always get aligned as they should, some Sub-District and District brackets will be much more unforgiving than others. Some kids will make it to State when others that are much better are sitting at home, and there will be times in high school that it also happens.
I spoke to a dad at Sub-Districts of a very good wrestler that didn't want to wrestle this year (probably U10 or U12). That was always my biggest fear and I am glad that day has never come. Enjoy it while you can, because it could be over tomorrow.