"No door I've opened yet has got me there, no. I'm not saying it's impossible to get back, but my original entry point...doesn't exist."

Which doesn't make any sense, either, but a paradox is a paradox.

"So I figured if I could manage to find Trudy, somehow, she could try getting the Bar and getting me back."

(Or, he thinks. Maybe the Bar has malfunctioned permanently and you're stuck here, and she sent you here to keep you safe.)