To be frank, I don't care WHO inspects the house. If the buyer feels good hiring their spiritual advisor or "buddy" to inspect the home, that's perfectly fine. There's just one simple problem...
If you aren't a licensed Home Inspector by the state you have almost NO CHANCE of having your repair requests taken seriously. The only alternative would be to hire licensed technicians for each part of the home, like HVAC Technicians, actual electricians, Structural Engineers ... and so on. Otherwise you could hire Chewbacca and the results would be the same.
There's nothing wrong with having grandpappy take a gander at the air-condition, or your uncle sticking his nose in the pool equipment, but if they aren't licensed, you're wasting your valuable time with negotiations. The only way you could possibly get away with this is with a FSBO as they usually don't know any better.
Some other points to remember:
1. The only person who would be allowed on the roof is a licensed roofer or a home inspector. NO family member should get on the roof, nor should they crawl through the attic or attempt to flip breakers or backwash the pool. Leave this for the inspectors. You break it, you buy it!
2. Special testing of the home should be communicated with the listing agent / seller. If you want to perform a hydrostatic that's fine, but get permission and communicate it with the other party.
3. You should never fool with the T&P valve on the water heater or attempt to "test it."
4. Viewing the home is different than inspecting the home. You'll have time for inspections, it's not something that you should try to have down while looking at the home initially.
Buying a home is not like buying an automobile. A lot of men want to think they know what they're looking for when they buy a car, but the hard truth is, they haven't a clue. You can drive real fast and slam on the breaks to "test the breaks" but that holds little merit with the breaking mechanisms of a vehicle. This is also why men stare at engines for twenty minutes when they aren't running.... it's as if they are looking for the problem when they have no idea what the problem even is. Sort of reminds me of...
"TURN IT OFF...OKAY, RESTART IT AND GIVE IT SOME GAS!"
"HONEY, TURN THE LIGHTS OFF AND ON!"
"PUMP THE BREAKS, TURN OFF THE DAMN RADIO, YOU'RE KILLING THE ALTERNATOR!!"