I can attest that regular simple green will etch aluminum if used in a high concentration and left to soak for a extended time.
It has been a staple cleaning product of every motorcycle shop(think massive amounts of bare polished aluminum) I have ever been in, mostly bought in bulk 1 gallon concentrated jugs. Mixed in a low concentration and not allowed to soak on the area I have never seen any issues. Typically it will be mixed around a 5% - 20% ratio to water in a spray bottle, the bike would get a quick rinse of water and the misted with the simple green, let it sit for around a minute then rinsed off to remove the heavy debris and oils from the repair work, then get a quick typical hand washing.
I use it on my own bikes and in the engine bay of every car we own. Do I think it is detrimental, harmful? No, just don't be stupid with it. It is no worse then winter in a state that uses road salt.