The clause is applicable to the ME Equipment. It is up to you to decide if this accessory is part of the ME equipment, generally yes accessories are included.
However, the requirement is stated for a cumulative time of 8 hours and can be adjusted for less time. With your vibration lasting for 10 ms (depending on how frequently they will be using it) the calculated acceleration limit will be huge and probably not a concern. You should estimate how much the button will be used, calculated the allowable acceleration using the provided formula, and check that the acceleration of your device is less than the limit using ISO 5349-1. Your test house will probably be able to do this for you.