I don't know the answer. Although I would guess a 4 year old average would not be good enough.
But since it is a scratch event the only difference is which division does he bowls in. Depending on your team average, his doubles partners average, and of course for singles it may not matter.
Classified Team- Five USBC members whose combined average does not exceed 900.
Classified Doubles- Combined average does not exceed 360.
Classified Singles/All-Events- Average does not exceed180.
Regular Team- Five USBC members whose combined average is above 900.
Regular Doubles- Combined average above 360.
Regular Singles/All-Events- Average above 180.