What I understand is that there is a jumper cable between the controller's port and the inputs of the buffer IC, and his question is what happens with the buffer if you disconnect the cable. What does the buffer see at its input.

Am I right Christian?

Well, what happens may also be concluded from the datasheet, but to be on the safe side, you could use weak pullup resistors at the gate's inputs. This will make certain that it always reads a '1' if the controller isn't there. As a rule of thumb, I'd say 100k Ohms or thereabouts.