Well, it's a good thing the HI has his priorities in order
Following the HI forums, it does seem these guys have a real love of expensive, fancy things with lots of blinking lights. Customers also get real impressed by such gadgets. I almost want to accuse some meter makers of deliberately exploiting this with their giga-dollar briefcases of weird and unusual test equipment.
The trouble with these things is that they provide not facts, but 'factoids.' That is, a fact that may or may not have any relevance.
"Voltage drop" is such a thing, that means nothing by itself.
If you have a gradual drop over the length of the circuit, there's no problem. If all the drop occurs at one point .... then there's likely a problem that needs fixing.
If you have 10% drop on a supply voltage of 128 (common in new tracts), you still have plenty of volts for any appliance. Knock even 5% off a 108v supply (not rare in older cities), and you're damaging things.
We've had a number of discussions about HI's; some have become so passionate that they had to be edited. I suppose that they're a necessary evil -having seen some of the crap 'upstanding citizens' try to foist on purchasers- but they can't walk on water (last I looked).
Ultimately, it comes down to 'who's the authority.' That's where you make clear that the HI is but a well-meaning amateur, and your opinion outranks his. You have the license, and he does not. It is, as George Bernard Shaw said, far easier to be critical than correct.
Examine things yourself, form your own opinions, and let them pound sand if they don't like what you say.
