> however, the person that received it is also a minor of the same age thus also inappropriate to charge them

No not really, sharing sexual images to others that were shared to you directly by a person should be (and in some countries is) a crime. The boy in the linked case should be the one charged with the distribution of child pornography, or something akin to revenge porn since they are both minors.

It is probably very hard to carve out these exceptions for minors sexting, but we already have (in some countries) consent laws that factor in relationships between minors. I don't see why this would be different