Jimmie, u are mistaken on the design of that datsun system. The "loop" is not in direct line with the flow of fluid to the slave.
Fluid flows to the block, which is really nothing more than a Tee fitting. Fluid goes out one side of the block to the slave and out the other side into the "loop". NOTE: The other end of the "loop" is connected to a different fitting, that looks like another block. NO FLUID flows through that line and out the other end! There is no other line connected to the fitting at the end of the "loop". The "loop" probably has an air trap since it bends vertical and returns to the upper block fitting. Obviously, it cannot be bled, (and filled with fluid), unless there is another bleeder valve on the upper block.
As George said, that line "absorbs" fluid by having an air trap, a spring and piston or some other arrangement to allow flow into that closed line. The whole system is designed no different than any standard surge tank/expansion tank setup that is connected by a TEE at any point in a fluid flow line. Such tanks are common. In fact, the radiator overflow tank on any vehicle is EXACTLY the same principle.
That datsun setup is NOT a bent coil of tubing that somehow affects the operation of the hydraulic system in the way u have been claiming.
It doesnt take an engineer to see and understand that.