Jack's not about to shut the doors of the TARDIS but once he's sure the other man comes inside he's going to consider a demonstration. Jack leans himself up against the railing the bottle of Scotch being placed on the jump seat. "Help yourself to the rest of the bottle."

"Do you want to prove that you're immortal?" Jack asks him, he can seal off the TARDIS to keep any of the others from coming up to find him and to hear a gunshot go off. "Your Vortex Manipulator should be working then seeing you didn't burn it out while looking for him."