Hi Weidong, Hello Kelvin,
Actually, [2] only refers to the pads that carry the analog signals in the NHS3152 IC. The comment does not apply to pad 10.
The reserved pin has an internal weak pull-down, and can be left floating or tied to ground. The PCB designer(s) of our test boards always tie it to ground, to ensure the pin can never be high.
So the end recommendation stays the same: it is best to tie it to ground.
Best regards,
Dries.