I believe you could safely remove the lower jack screw.
No there is no MEL provision for it so I do not propose to make it standard practice but with a one flight home Engineering Authority from your tech services dept would be enough to cover the paper work legalities
The CF6-80 744 767 and A330 have a pneumatically driven T/R.
The (CDU) Centre Drive Unit provides the drive and the braking to the upper and lower jack screws via flex drive shafts.
A TRAS brake is fitted above the upper drive actuator to add belts and braces to the system.
I believe the T/R system has enough redundancy built in, that it’s stow forward integrity would not be impaired by one of these flex drive shafts shearing.
So if you had the situation where a jack screw had seized I think it would be feasible to send the aircraft home with the lower jack screw missing after checking the integrity of the other to jack screws, the drive shafts and the T/R brakes plus fit all the locking screws thru the forward edge of the sleeve.
This of course is well outside the authority of my LAE license and I would not carry this out without a piece of paper giving authority to do it.
In my time I have spent many hours on these T/R systems and have often found TRAS lock (short) flex drive shaft sheared and occasionally a long flex drive end sheared but what is most common is the CDU failing it's brake torque check with no associated problems written in the incoming tech log
My 2 cents
I just noticed the original post was made April 1st