Which bothers you more, 12 yr olds looking at models, or 12 yr olds looking at swimsuits?
Is it appropriate for 12 yr olds to go to a pool, beach, lake?...Aren't those swimsuits worn in public?
The purpose of the SI swimsuit edition is to arouse prurient interest. That may be fine for adults, but not for children in school. The schools are entrusted with the community's children and are (or should be) held to a higher standard than the general public at pools and beaches.