I have an ultra-sonic cleaner that I use in my goldsmithing business. I use a Simple Green and water solution for cleaning, 1:4 ratio.
I have degreased everything imaginable from diamond rings, BBQ parts to motorcycle chains using Simple Green.
I have seen absolutely no evidence of any harm to anodized or plated parts in Simple Green.
Other than anecdotal comments from people who don't know any better, Simple Green is safe for all steel, silver, gold, bronze, plating, rubber, plastic and anodized aluminum. I would not put pearls, turquoise, or opals in it, but I have had no problems with gun parts.
It did take the locking glue off of a Remington 700 factory trigger.
So show me the facts Jack: What did Simple Green damage, and what were the circumstances? Boiling in Simple Green? Soaking for six months? Put some money where the mouth is.
Anything I can't stand is a nitwit badmouthing a product he has never had any experience with.
I have no commercial interest in Simple Green.