Ugh... As usual, I'm not a fan of the writing style of the author.
First, this article say there has been one issue with aspirin
https://www.adn.com/outdoors-adventure/iditarod/2017/03/01/vets-check-iditarod-sled-dogs-lungs-hearts-and-gums-before-clearing-them-to-race/, I also seems to remember that for some years ago a couple of mushers tested for something (back-packers).
But I'm spotting several problems here.
ITC still haven't got the message about transparency, no news there, but they chosen some weird path in the middle. This is a problem I see all over the place, people are afraid of sharing information. If you actually
ask those people what they are afraid of they seldom has a good answer, they reallys just don't know. Bad habits is hard to break. I'm working with open data (in the IT world) and we see this all the time, unfortunately.
I also think this would have been easier if they hasn't been a stand alone organisation (as I think they are?). With that I mean, they don't use IFSS or WADAs or other international (or national) set of rules, but they make the rules themselves. To compare to my world, we have a set of standard set for licensing. The good thing when using something standard? Everyone know what the rules are and the lawyers love them since they are well known. Much better than inventing the wheel and later figuring it didn't cover all the bends you needed.
The third problem is probably just because I'm from another part of the word. In my impression, no one dares to do anything in USA because they are afraid of lawsuits. So this just kind of confirm my impression, lawyers figure it might be not clear and then they don't want to press on. And if you are afraid of lawsuits then you can't tell which team it was either I guess? This is just my impression.
I think they should have told what kind of substance it is or if they don't plan to tell anything, don't say anything at all. Just change the rule because it need clarification and skip the rest.
I totally agree that the musher should be responsible, I realise you can argue that some might tamper with the bags sent out on trail, but if the musher isn't responsible you will never be able to prove anything.