I know it's the oils in the tire "evaporating" that causes dry rot, like to use silicone on other rubber items to prolong life/keep lubed (like door seals, for example).
Wonder what there was in Armor All that tended to dry out tires...
Largest problem with "shine" products in regard to motorcycles was people getting the stuff on the tread, you can see the problem with slippery tires there. (grin)
It'll be interesting to see more comments on this, apparently some products DO work in extending tire life/appearance.