I guess it depends on what you want to hide: Is there anything between the plant gate and the machine that you "know" the inspector should not be allowed to see? 8<)
No, I would not recommend you allow him/her unrestricted access to your plant (open the gate and tell him to "walk around until you get done"), but you should be operating correctly and safely as a matter of routine. Since you indicate the inspector is going to be "investigating a complaint" - he/she is going to arrive suspicious and will be deliberating looking for flaws or errors, and, in particular, for any conditions or safety violations you are trying to hide or minimize.
So, follow your plant's published and EXISTING "escorted visitor" safety policies and PPE and training: Give the slideshow or video, make sure he/she has all the right PPE and the right clothing (fireproof/fire resistant clothing/steel-toed shoes, hardhat, goggles, hearing protection, etc.) and then take him to the machine, take him back to the machine, allow time to answer the questions back in the office, etc.)