He doesnt avoid it he is explicit. To conclude that mono was more revealing they would have had to do plenty of test work with stereo as an alternative.
From the video here:
"without exception", "every time" the mono preference was the stereo preference.
So this tells us that any timbral change from mono to stereo is not significant enough to change the preference.
OK, so what if you have a set up with a 2m x2m x2m triangle and you apply some EQ (whatever that might be). What happens when you change to a 3m x 3m x 3m triangle? The required EQ will be different. So considering the potential variation of set up and room you could have an infinite number of appropriate EQ settings.
However we know from the testing Toole has performed that it doesnt actually matter what room or setup you configure, the preferred speakers remain preferred. Again form the video