My point is simply that without a directive from the government, it would be illegal for the conference organizers to physically detain you, even if it's to isolate or quarantine you. Even if they did have a directive, it would probably still have to be a sworn officer doing the detaining (there may be case law on this to the contrary). Hospitals obviously have such a directive, but I'm not sure that even a hospital security guard who isn't a sworn officer would have the power to detain you under the hospital's directive. In any event, it's not at all clear to me that HIMSS has a directive from a government agency, let alone that the detaining would be done by sworn officers and not some hired help with "guard cards".