I would be interested what you read about simple green.  Can you tell us more about that or where you found it.  I have been using simple green for years and I don't think it is an issue.  I usually mix it somewhere between 10:1 and 20:1 with water and it is also absorbed pretty well with a terry cloth type rag.  I could see how it might not be great for the paint if it's not mixed with water enough or if it's not wiped off enough or it could have more of a long term effect that I am not aware of but I don't think so if it's used right.