[Steve's seen plenty of guys with shellshock (okay, that's not what it's called anymore, but it still seems appropriate, just at the moment, because Stephen seems like he really is in shock) and being anything but calm, here, isn't going to help, he figures.

He squats down to get more on Stephen's level, but doesn't grab him - just puts a hand on his arm, carefully.]

Then we should get it looked at.

Stephen, I'm not gonna take you to Zero. Do you really think you need to be down there? You need to tell us what happened. [Because Vex can't.] I'll take you back to your cabin.

[He figures if Stephen needs to be confined, that's the better place.]