I'd wager they were targeting a particular pax on your flight who'd been profiled in advance. They can't meet every flight with that sort of manpower.

Speaking of jetway intimidation, the story reminds me of the time I was boarding a BA flight at LHR T4 a few years ago... at the head of the gate you produce your BP and passport... well, the BA gate agent made a slow, solemn show of taking each passenger's passport in hand, scrutinizing it, then holding it up to show the photo page to two lumpy, unsmiling men in nondescript suits standing on the other size of the passenger queue. Each time he did so the two men would stare at the passport and the passenger, then gravely shake their heads "no." Whereupon the pax was allowed to board.

I never did find out what the heck that was all about but it was obviously some sort of theater, staged for some specific person's benefit. And so was your incident, I'm sure.