pin 0 will act like it has an external 1k ohm pull-up.
That is true - I am becoming a little bit unconcentrated at the moment. The good news is, that this is independent of what is going on at the other side of the chip. Be it no power from USB, no active connection, no bytes sent - in all three cases the FTDI chip keeps this line HIGH.
This however will not change anything of the concept, it is now wired-AND rather than wired-OR.