HIMSS is using the word "isolated" [1]. HHS defines "isolation" and "quarantine" as the following [2]:

"Isolation is used to separate ill persons who have a communicable disease from those who are healthy. Isolation restricts the movement of ill persons to help stop the spread of certain diseases. For example, hospitals use isolation for patients with infectious tuberculosis.

Quarantine is used to separate and restrict the movement of well persons who may have been exposed to a communicable disease to see if they become ill. These people may have been exposed to a disease and do not know it, or they may have the disease but do not show symptoms. Quarantine can also help limit the spread of communicable disease."

Seems like the only real distinction is in terms of whether on not you're currently ill, but fundamentally they both restrict movement.

From HIMSS [1]: "Screening procedures established by the CDC will be conducted on site throughout the conference; HIMSS and the Orange County Convention Center will consult health teams at Orlando Health when necessary.

Should screening reveal an elevated risk for an attendee, the person will be isolated immediately to prevent exposure to conference participants."

[1] https://www.himssconference.org/updates/himss-update-coronav...

[2] https://www.hhs.gov/answers/public-health-and-safety/what-is...

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".