"Locking the Front Doors at 9pm"

My parent had been a patient in BHH for several weeks and this was not their first visit to BHH, where they have had lengthy stays. My parent is an elderly patient with Alzheimers Dementia. I would like to know why the security guards on the front door felt the need to refuse to let my parent in the door and make them walk all the way around through emergency? I have discussed this with security and I feel that frankly, they don't care at all if my parent is elderly or has dementia. Sometimes my parent has no idea where they're going. Yes, my parent is a smoker and went out for their last smoke around 8:30pm before they lock the doors, but sometimes they lost track of time and didn't get back to the front door before they lock them at 9pm and they refused to let my parent back in. I would think that the security guards have a duty of care to the patients in the hospital to let them back in the building regardless of what time they come back inside and not make them walk all the way around to emergency to get back into the building. This concerns me greatly for the welfare of my parent and many other patients who I believe have had the same problem. I would like an answer on this, please.