That is a pretty legit 5000 for his age.
Does the US have any historic performances that are comparable?
I think it was 13:55 that Chris Derrick ran at 17 and Rupp was 18 for his 13:37. Of course German Fernandez ran his 13:25 at 18, though that's a big age difference. What have our youngsters run? A quick search didn't bring up much for me.