Given Tsurara can use her powers to manipulate ice and snow, I can't see how we could be sealed in.Actually, I can see good reasons. We go down the wrong tunnel, enemy comes in from behind us. Or possibly seals the tunnel behind us, and gets a win or a head start that way.
If his goal is just surviving us, well, that's a good way to beat 2v1 odds.
Let's see if I can post a pic...