Happy New year Hifimad
I know you have told us of a personal bad experience in the past.
I can't comment on the situation you speak of but can only add if I was concerned I would have walked away and informed the police of my concerns and let them attend and deal with it.
i fully understand your position and would usually agree with you, however these people in the past have operated with the full support of the police in their law breaking, i speak of course of them instructing the police to unlawfully detain someone they knew beyond doubt was innocent of any crime and the police could not jump fast enough, also the handing of privelidged information of complaints i had made to police proffessional standards to these guards to enable them to post it online a criminal breech of the data protection act by both the police and the guards who posted it, the police do not give a damn about the guards lawbreaking.