Does This Constitute Wage Theft?

I am an RN at a hospital that like many others in the US just experienced an uncharacteristically severe winter storm for our area.

In preparation for the event the hospital system activated their winter weather plan and directed dayshift staff to report to the hospital at 8pm alongside nightshift staff. The dayshift staff was then assigned areas to sleep with instructions to report to their unit at 630 am and we were told conditions would be reevaluated at that time. At 630 am conditions were as bad as forecast and everyone was informed the weather plan would remain in effect, nightshift workers were assigned places to sleep and directed to return to their units at 630 pm.

However at 11 am administration made a decision to end the inclement weather plan, and notified staff VIA EMAIL that they should assess risky and safety in making decisions to travel and extended an offer accommodations for staff that voluntarily chose to stay on campus. As a note the area was still under an official winter weather warning.

I feel like the hospital is walking inf a legal grey area here because they did not want to compensate staff to stay at the hospital all day or maybe i dont understand the laws. Is it really legal to tell someone they have to stay at work, direct them to sleep, and then communicate that their stay is now voluntary while they are asleep?