I worked in security, oops, not supposed to call it that... Watchman duty for several years. Watchman duty is divided between external and internal. A fair amount of each section would have radios so they could feel all James Bondish. If anyone approached the Convention who didn't look like a typical JW robot, they were observed all the way to their seat. If they gave obvious signs of wanting to start trouble, they would be confronted by at least a couple of JW Watchmen (aka Barney Fifes) who would try to discern their intent and either escort them to a seat or escort them off the premises depending on how they responded.
The only way that Emma's story makes sense to me is that some local JW must have known you guys had "apostate leanings". Lack of a lapel badge alone is just a minor yellow light in the eyes of the Watchmen, IMO.
om