Yeah, from what happened with a friend who was in one for a week, they take away your phone as well and don't let you access it until you leave. I think with that it's partly that they just want you to focus on your care, but also I imagine the fear that someone could call or send a text that upsets them. And she was suicidal but hadn't made an attempt either--she was handcuffed and taken by police because they thought she was a danger to herself. It could be with Jo, they told her at the first hospital where she was that either she had to take herself to an inpatient facility, or they would forcibly commit her.
And I do understand how she could have reacted that way to meeting and talking to her mom. Even leaving aside what her mom said about being unable to look at her, I would think just learning you were the product of a rape would be traumatic in itself.