He follows along, and follows Jack inside the TARDIS, at which point his expression falls to almost completely neutrality, because that's... just wrong on some level he can't explain and doesn't want explained to him. "Nice," he says, mildly and blandly. "The last thing I remember before I got picked up by some future-and-possibly-alternate-for-me version of the Doctor was getting shot by a Dalek on Game Station."

He's just... down to business, staying relatively close to the door, leaned sideways with a shoulder against the wall, arms crossed. He's never seen the HUB, Cardiff or otherwise, so it's not familiar but it's obviously a TARDIS, and he's not going any further into that thing. Not one owned by any version of him, anyway.

Why yes, he does trust the Doctor more than himself, regardless of version.