Not true. With an "n" of 4, his observations are far from statistically significant. And what is his 75dB reference, anyway? How does he know that 75dB on the digital meter is actually 75dB? You can't really say anything about the accuracy of any meter without a gold standard.
But it really is irrelevant if all you want to do is calibrate your speaker channels to the same level. The meters are quite precise, actually.
And I have no idea what "reference is 115-117dB on the digital meter with MAX turned on" means.
"All men are frauds. The only difference between them is that some admit it. I myself deny it."