Russ - not sure what tire you're running, as that can change the gearing as well, but in any case that is an absolutely MASSIVE gear. Very seldom does a top rider run very far above the classic 55 gear inch BMX standard (44:16 on 20x2" tires, roughly)
My kids are running:
9yo - 42:16 / 54 gear-inch / 170" rollout
10yo - 40:15 / 55.75 gear-inch / 175" rollout
I'm running (as a 42yo inter):
44:16 / 54.9 gear-inch / 172.5" rollout
I definitely want to lower the gear a little for my 10yo, and I think I'm going to try going back to 43:16 for my own bike at my next race.
What your son is running:
45:14 is 64-65 gear-inch / 202" rollout.
Kids around that age can sometimes be successful running slightly higher gears than older kids because they often have trouble spinning to the same max cadence, but I'd say that is pretty extreme. Even the pros run less gear than that on the 8m start hills. Acceleration at the start is generally accepted to be far more important than pedaling later on the track.
BMX Ultra gear calculator is a pretty good resource that takes into account tire size as well.