Well, well, well, it's looks like I may be uniquely qualified to respond to this post. I WAS at the Outlaw race in Snellville, I DO race in the Florida My Series races, I DID run a non-O/S body, and strangely enough, my cars are ALWAYS yellow. Hey I'm even (way) over 55 but that wasn't what Brian was talking about, that was actually the number of entries at the race among the three classes run.
I'll have to admit that I didn't inspect EVERY car entered as Brian must have to verify which make of body was being used but I will say there were alot of O/S bodies. That said I don't know how old they all were and I don't know if Brian knows that either. The O/S Bentlee I used in GTP was well over a year old and purchased when I could get them easily at most any slot shop, which in my personal experience is NOT true now. For instance, there were no O/S Nascar COT bodies available on the wall at Flashbacks when I got there on Friday afternoon. Luckly I was able to borrow one from one of the other entrants and I did run one in the race, hey, it was even yellow, what luck!
I have to say the Nascar body I ran was very, very thin but that is legal in the Outaw series so no problem there. But what is a problem is the usual quality of the O/S bodies which is to say they tend to run thinner than advertised (to say the least) and are usually thinner on one side than the other. This is why one of the retro organizations had to change the body thickness rules and has to scrutinizes the O/S bodies so closely at the races. Couple that with the real availability problems I've experienced and heard about (from first hand sources) and I can understand why My Series has outlawed them.
I know that Ralph Thorne is now a distributor for O/S bodies and he is quite responsive and easy to deal with for sure. However, I believe most raceways tend to want to deal with a distributor with a full range of products and not one with just a few specific products, it's just easier and quicker for them to do one-stop ordering.
So Brian to answer your concern, maybe if O/S would address the quality and availability issues the bodies would be allowed in My Series and would be under less scrutiny by the various retro organizations.