"Nose down" does not imply a trim adjustment, as the primary control in pitch is performed by the elevator, while trim adjustment, on this airplane, is done by rotating the horizontal stabilizer. From the fact that the pitch changed, we cannot tell whether it was commanded by the autopilot or MCAS, but as MCAS is supposed to be disabled when the autopilot is engaged, and this occurred when the autopilot was engaged, it appears less likely that it was MCAS than it was the autopilot.

Furthermore, the signature feature of the MCAS failure that downed the Lion Air flight was runaway trim, and there is no indication in this report that the crew had to take any action to stop it by disabling MCAS (setting STAB TRIM CUTOUT to CUTOUT, the documented procedure for doing so), or to restore the correct trim manually (as far as I know, it would not revert to the correct setting simply because MCAS was disabled.)