Perhaps I am misunderstanding the situation, and if so, apologies ...

It's my understanding that the person waiving folks through after the GE machine photo ("Robert, go! Elizabeth, go!" etc.) is the immigration (only) clearance. They aren't interested in customs issues.

My recent experience was that they've turned the post-baggage claim Customs exit into a Nothing to Declare zone, pretty much. As far as GE declarations are concerned, it's my understanding that if stopped for further, secondary customs screening, one can discuss (declare) goods before an agent opens a bag without risking one's GE status?