My thought is that the GA processed the VDB too early and OP's son might be the only person who got a VDB so that's why they had no choice but to call him back.
My 2 most recent VDBs, both within 1 week of each other had drastically different approaches.
First VDB was not processed until everyone had boarded and doors closed.
Second VDB was processed and I left the gate area with certs and BP for later flight 10 mins before boarding began.
So my thoughts are it all depends on the situation and next time, take off and run
