Conventional wisdom in quality circles leads many to assume that if an inspector uses it, it must be calibrated. This is a lot like the debate over firearms which, when you really think about it, are bits of machinery that do nothing on their own but can do a lot of damage if misused.
In metrology we have similar benign bits of hardware that can create havoc if misapplied, but in the grand scheme of things rarely are. But many companies include them in their calibration program, probably more to keep auditors from asking silly questions than for any other reason.