The Blue 2-1 has not been tested nor approved by the UL for motor ie inductive loads and AFAIK, the dimmer function is not designed for or rated for such loads.
The thread that you linked pertains to the Red switch (not Dimmer) which is rated for inductive loads but since it is a switch, will not vary the fan speed. There is a zigbee fan switch under development which will likely be suitable for your application, but the Blue 2-1 is not.