Leila knows the pros and cons of them staying here. But currently she really wants them to stay. To gather some info that may be helpful for them.
Harvey was also not able to make a decision right away. All of them have their point. And rashing to decide something may end up very bad. Especially their memories of the party are still so clear. They don't want to be targeted more than they already are.
So he left the decision to Leila. Someone whom he trusts not to let them down. This is a belief that he has made as time passed by with her presence.
"With the majority, we can just make them leave." Leila started. "Though Ryan is right about being humanitarian. We cannot also leave them be. So how about let them stay for a night, afterwards they can leave? Just that we must save as we must and conceal as much. Besides, we can take this as a practice in case something like this happens again. After all, we will not be students forever."