Just because you may convincingly claim they have less risk getting a vaccine does not determine if they they should therefore get the vaccine. It is a very small margin of risk either way.
It is larger than you realize. The risk of death is small, but the risk of severe disease, hospitalization, and "long-haul" effects is large. Much larger than for chickenpox, measles, mumps and other diseases that all children must be vaccinated against. If we are going to vaccinate children for these other diseases, why would we not vaccinate them for COVID? I do not understand why you have a different standard for this one vaccination, for this one disease.