Originally, Ian had planned to have Mina locked up in a regular guest bedroom, but she had tried to jump out of a window at the hospital, and he could not risk her dying before he figured out who sent her. So he and Luna decided to put her in the room she was now staying in. The only way she could kill herself there, would be if she hit her head on the furniture and that would take extreme willpower and strength. He didn't think she had the guts to take her own life, but he couldn't afford to be wrong. She looked very determined in the hospital. If he had not caught her in time, she may have actually jumped.