As long as he does not react to the door
closing in a negative manner, you can leave it closed a few moments longer each time, staying in direct sight.
Their mere presence is not a threat or assult of course, but if they are attempting to deterre someone from acting
in negative manner the security personel would likely have to get
close to the person and make demands that they leave or stop whatever activity their engaged
in in a
manner that could be considered a threat of force if they don't comply.