My guess is that Elon realised that he needs to shut up about this because it is likely going to be one if if not the most valuable parts of the company. A 10x improvement in manufacturing would lead to an unassailable lead in vehicle cost. Also, it would be a large moat becuase other companies would take significant amounts of time to be able to innovate in the same way, all why they have to either lose money or sell more expensive vehicles.
Elon doesn't need to shut up about AD progress and plans. He just has more than enough to publicize about products that customers will actually buy one day. The ICE companies aren't going to invest billions to make their soon to be obsolete IC vehicles 5 x faster.
Neither will they invest additional billions to make new EVs five times faster when they don't have battery cell supply to reach a few million collectively before 2025.