I don't have any anecdotal evidence of my own but I will say that alkalines ARE corrosive to aluminum. Every double-wall rim that I've seen has raw-edged holes bored through the walls for the spokes -- likely places for an alkaline to attack.
This is a severe example but I did a bit of a double-take at this (had no idea Simple Green had alkalines):
http://www.mechanicsupport.com/aircraft_cleaning.html