I have tested - and used - the ATF/acetone mixture and found it to be very effective. It's never damaged the (blued) finish. I keep a small covered glass jar in my outdoor shop, never seen any damage there either.
The problem with acetone is that it's extremely flammable. The ATF mitigates that, but the mixture still should be kept well away from open flame or sparks just on account of because. I've not tried to light it to see if it's really safer.
By the way, acetone is actually produced by the human body as a normal process, and is used (in compound with other materials) in treating epilepsy. It is not an aerosol poison.