It makes sense to me. [Because Time Lords are weird.] We have rooms that can perform similar effects. To us, anyway, there is both the time that passes, and the alteration of your own perception of time that passes.

In any case, I don't think it's impossible. Any more than my coat pockets are. [And he puts the whole mongoose down in his coat pocket with that. No wiggly lump or anything. It just seems to be gone.] One step at a time.