(((When automatic landing is initiated, users can now continue to control the aircraft’s position and altitude. During this process, the maximum speed of ascent is 1 m/s.)))
So the way I understand the above detail given by DJI, is they want to make sure you are going to land the quad and not attempt to keep flying. Could this be because there could be some other unknown source coming along that will have the ability to force our quads into Auto Land? 2.24mph
Edit:
Btw, DJI now wants us to know about their liability claim addition as well. This was found at the bottom of the download page.
* Notice:
As DJI Innovations has no control over use, setup, final assembly, modification (including use of non-specified DJI parts i.e. motors, ESCs, propellers, etc.) or misuse, no liability shall be assumed nor accepted for any resulting damage or injury. By the act of use, setup or assembly, the user accepts all resulting liability.