Yes, common sense should be used.
"BUT if you take that perfectly tillered bow and alter the mc levels one limb relative to the other you don't have a perfectly tillered bow anymore now do you?!?"
Well, maybe. It depends, I think. Common sense tells me any potential effect of moisture differences in a bow's limbs would be relative to the actual moisture content(s) within the bow... meaning, the 2% difference between 12 and 14% may show a noticeable effect while a 2% difference between 7 and 9% may not. Common sense also tells me that any such difference(and/or higher level of actual average m.c.) might only have a noticeable affect on a limb if it was also already borderline overly stressed due to things like design shortcomings, or limb balance disparity... again, relevant to degree. I think common sense helps me remain objective about this as my bows are always stored vertically and their bottom limbs seem no worse for it.