G'day Bill,
I can be wrong...I just can't remember the last time it happened

, my recollection of the banning of steroids was that the main reason was an animal welfare issue ( and I can attest to the truth in that, as I've witnessed a case or two).
Putting that aside, anyone using steroids on a horse in work is asking for a painful outcome as there is no guaranteed time frame for their leaving the horses system...sort of a russian roulette if you like and like it or not there has to be a line in the sand somewhere.
Because whether it's tuf or not, the rules state none in the horses system when you are competing ( I honestly thought none fullstop and will check as best I can).
So mate it's not Mark and I making the rules, simply saying they are there for everbody and if you want to play russian roulette then do so knowing the consequences, because tuf or not Bill, if one horse is going around with steroids in his system and the others are not then he has an unfair and illegal advantage over the others...I'd call that cheating, you mate can call it what you like.
Cheers,
Dan