The reference to the SIL rating table is critical.
SIL stands for safety integrity level and represents a reliability factor of a safety product.
For example, SIL 1 means there is a 99.9% certainty that the product will function as needed.
SIL 2 takes that to 99.99%.
SIL 3 goes to 99.999%.
The table in section 2.26.4.3.2 says the inspection switch should be SIL 3.
For the code to give an "either or option", that is mechanically activated or SIL rated does not make sense. It should be SIL rated period. Just because a manufacturer can claim a switch is "mechanically activated" does not mean that it has the same safety integrity as a SIL3 rated device.
