Leah, I feel for you. I can see that situation being repeated anytime, anywhere ... as stevielynn pointed out, the phones are ubiquitous. (yes, I have one too, although COMMON SENSE would prevent me from ever taking someone's picture without their permission, except at a public event where it's expected)
Not sure what to advise you ... I haven't had someone take my picture - yet. I've had a few unpleasant *discussions* in triage. Overall, our security staff is pretty protective of us, but I can see them being reluctant to confiscate private property which wasn't an "obvious" threat such as a weapon. At most, they might decide the person was "belligerent" enough to warrant being escorted out, but that would probably be a stretch ...
Hope you have a better day today.