Kenny, I just checked and the word 'any' is removd. It's what I recall from initial training in 2010. Now it says 'visits to the flight deck by passengers are not permitted'. Nothing about captain's discretion etc... so if crew were going to be literal and follow it, no pax is no pax. Of course the skipper has the authority to say who can go up (then again these days, what is captain's authority worth given certain cases) also given that no one wants to get fired this may explain why you may have noticed a drop in the number of pax being brought up after landing...
It then goes on to say 2 points later that access is restricted to operating crew only. Again, nothing about ground staff etc... really should be worded better. For interest, 10.6.4.2 and 10.6.5.