One of the original articles about this had said something about the fact they had already seen her, did tests as they deemed necessary, discharged her (as we usually would with someone we thought had a sprained ankle), and she refused to leave which is when she was arrested for trespassing. It wasn't that they refused to treat her or give her the medical screening exam. It was that they were trying to discharge her and she refused to leave (as many homeless will do).
Why? Free money is free money. If she had a negative doppler yesterday, that's pretty damn defensible unless the exam showed marked worsening of pedal edema. I just had a guy that had a full LE doppler that was negative come back 4 days later with a completely occlusive clot from the common femoral down to the pop.