Having worked on the mapping of the touchpoints when FLY was introduced and we needed to re-do conformance I can say that it's not the case. The HAL gates that "talk" to BA's services are those at front of house, as you enter the security queue. A scan there generate a marker for locating purposes, create an airside locator as well as a check against conformance. The scanner at the top of the queue for the security machines, to my knowledge, is not linked to BA's systems.

The reason why one of your party was called is because there was no airside marking against this person, and thus he/she was at risk of being offloaded. The system would do it automatically, but luckily a human (I suppose the ADM, or gate lead) checked it and saw that they were in a group.