if you're sitting there, quietly refusing to leave, the cops just simply don't have the authority to remove you from a hospital for "trespassing" - just like they wouldn't have the authority to drag you out of a public park, or out of city hall. 

all the cop did was state the trespassing law. she had no idea. there's no case law cited at all.

these cops have, on average, something like a grade 12 education.  they're screened for low intelligence, on top of it. so, it's not some kind of accident - the system is designed to be impenetrable.

but, this is why we have activists, and this is what we do.