Who's in the wrong?

So where I live we have Giant Eagles that will not allow anyone in the store without a mask regardless of medical issues. Its posted all over the doors they MUST have a mask on to enter. There was an older gentleman who entered with an oxygen tank and no mask, he had his older granddaughter with him. He was asked to leave the store for not wearing a mask and offered by the manager to finish his shopping, the granddaughter started to flip out and throw a big scene and they both got kicked out. Was the manager in the wrong or customer?

I'm just curious, shes posting all over FB about it and I feel the manager was in the right, its stated everywhere on the doors and throughout the store. And why couldnt the granddaughter do his shopping since hes already prone to get the virus and possibly die from it?