Even with the deal with the gods they still don't claim all of their kids. Percy can only think how many kids are 'troubled' and trying to protect themselves with whatever they can find. He's still busy with starting the surf school so he can't just go to schools with Grover to scout. Maybe...he just could send out a warning? Hevey canon divergence because of timelines and stuff..also takes place before "I am thou, thou art I" timeline wise but they don't have much of a connection...yet.