Unprofessional behaviour from Pick n Pay security staff

I am a regular customer of Pick n Pay and go there on a daily basis. After this experience i doubt that i will frequent there again and would rather prefer going elsewhere. On the 29th of May me and my son walked into Pick n Pay in Vredenburg on the westcoast. My son had a little bag in his hand with a small toy and two door hinges which we bought at the chinese shop next door. Whilst walking through the door the security guard ran towards my son and wanted to grab the bag from him. Before he could grab the bag from his hand i stopped him and told him that he should not grab the bag from his hand and he should ask me. He then continued to say that he just wants to tape up the bag. I took the bag from my son and opened the bag for him and told him that i go to Pnp every day and i know that the shop does not sell these items in the store. He then said that he tapes all the bags. I said that he should reason with some sense and think for himself that his rule that he is applying should obviously be uses within reason. He was adamant that he has to tape it so i took the bag to the parcel counter and told him that its a stupid rule and that he cannot reason with sense that since the items were not even sold there that there is no risk that i would take items from the store. I have since stopped shopping at PnP and rather prefer going to checkers. They dont treat people like ********* and they also have security guards that behave professionally and dont grab items from peoples kids.