We could use it as a safehouse for our own number.

[That was more or less what he thought Graham's intentions with asking Sai to open it for him were, tbh]

There are plenty of locations we can take the civilians, but no others where we can maintain track of their positions, correct?

As for escaping forcibly, there are various options I could offer. I can create explosive tags to blast open the gates, or use fire, or ram it with another ink animal...