Calling it a RepRap, with full explanation that that means a printer that can print itself, does make it sound like it could be a goal

But even if you could get a positioning system that small, I'm pretty sure you can't scale resin printing down three orders of magnitude smaller than this printer. Maybe a tiny CNC?

Or more likely they refer to eventually printing the mems devices used in the printer

None of the reprap 3D printers can fully make themselves. They all still need additional parts that can't be 3D-printed, like motors and controllers.