You are correct about ammonia with copper, brass and especially nickel. I'm not sure if #9 has ammonia, but may contain a little as it removes and prevents fouling. That said, I think repeated use may be detrimental. I would use it once initially, squirting down onto the spring. The black gunk would ooze out, then I would blast it out with compressed air, dry it, and flush with mineral oil. Your post made me a little paranoid so I went and checked a couple stag and wood examples I did some time ago. Brass and pins nice and shinny and no verdigis on the stag or brass (which would happen with a chemical reaction), so no harm-no foul here.
Actually, over the last year or so, they have done a much better job of flushing them clean from the factory and have had pretty smooth action right out of the tube. I pretty much just do an oil flush now. Thanks for pointing this out though.