He wants to argue, but they're wasting time. There could be people out there who need their help, so instead, he opens the door and holds it for her once they get to it.

"After you."

The worst part of them both being invisible is that he won't be able to keep an eye on her. Maybe she's just as capable as he is, but he still wants to have her back. They don't know what's out there, but he can't imagine that it's human or easy to deal with.