Dude,
To be honest I am not sure what to make of his scores. Is he really gifted or just a smart boy? I think just CoGAT and ITBS dont tell me that. I am hoping further testing might help with that question.
Even if the school will not use those results I might be able to afterschool him better. Applying to programs like the Young Scholars seem require such tests done too. So it might be worthwhile to get it done.