For whatever it’s worth, their Emergency Room entrance has a little “no concealed weapons” sticker on the doors. The entrances to the main hospital does not have stickers, though. Of course, they can only ask you to leave, so… You do have another option – which may or may not be your cup of tea. The sticker refers to “concealed weapons”, meaning that if you are willing to switch to the open-carry club – you are complying with their wishes, but will still probably wind up on the asked-to-leave list. No biggie, since your car’s probably parked right outside the door. Just lock it up in the trunk.
It is my understanding the reason for the no-carry rule is that emotions run high in the ER. People come in messed up from fights and accidents, people die, and all kinds of other bad stuff. This explanation makes a lot of sense, given the above-statement regarding the main entrances.