I tried this more than a year ago. I didn't have silicone spray on hand but used some spray for vinyl. It dids increase spin noticeably, but wears off after about 30min and left marks on the tennis balls. Maybe silicone spray will last longer.
I neither agree nor disagree with the proposed ban. Some people have been doing this or with wax on gut for years. A gut string job I got from TW had quite a bit of wax on it. If you string for yourself you might have noticed there are also several strings that come packaged with a light coating of lubricant already on it.