She doesn’t have a choice

“I….” Liara tried to figure a way out, but she couldn’t. “I’ll do it.”

She couldn’t let Shepard be hurt. She had to buy more time. She had to try. “Very good,” Brooks said. “And know that you will be monitored at all time. If I even think that you’re trying to scheme or help Shepard, the deal’s off and Shepard’s reputation will be splattered across the extra net.”

Liara was then grabbed and released from her restraints. She was blind folded and gagged as she was brought through the prison and eventually transported out toward the Citadel. When she was let go she was back in her normal clothes as if nothing happened, but she knew better. Her jaw dropped as she saw Shepard sitting against a wall, looking so… defeated.