That (one elderly couple pushing a grocery basket, being followed by SIX Security People??!!) must have looked rather odd, perhaps even conspicuous.
Other shoppers might get concerned for the apparently oblivious couple, and call for assistance.
“Ma’am, excuse me. Don’t look now, but there are five or six men wearing black suits and dark shades, who seem to be following you all over the store! Everyone’s lookin at them. Should I call Security?”
They have an entire platoon of security people but don’t trust them and are too paranoid to allow 2 of them to go buy their groceries for them.