(I have no idea if Campy specs a torque for that particular bolt)
Since the bearing play is set by the collar the only function of the bolt is to keep it in that position. Campa suggests you tighten it untill the gap in the collar closes.
I've seen shot bearings from a single ride with that much play.
The play was probably caused by excess grease being pushed aside. Most LBS and even the factory itself stuff way too much grease in the hubs making it nigh impossible to adjust the bearing play in a single run. 2.5mm play l/r is often the result of it after the first ride.
That said I can't really fathom how a single ride with that amount of play (any amount really) can ruine a set of cup and cone bearings. But...If you say so...