That's the question, isn't it? If she is sure that she herself didn't take it she needs to find out how it got into her system. I'm sure the investigations in her team are ongoing. If they find out how it got into her system then you're right, no need to try to have the B sample tested. But if they don't only three possibilities remain:We're repeating ourself again and again. The testing of 'B' sample is taking long time, weeks at least. They didn't want that delay. She basically thought, 'Oh man, I just stopped to use it in November so there probably some traces left in my blood'. See? She thought it was traces AND if she thought that, it means that 'B' sample will contain traces of Mildronat too. So there was NO POINT of testing that 'B' sample. None. Zero. It would only be a wasting of time. So they decided (I'm sure it was not Katia's sole decision, but the Fed's as well) to fix that 'misunderstanding' as soon as possible and contacted WADA. When WADA responded, and Katia saw the amount of that thing in her blood, it was once again pointless, not to mention too late. Because it's there, in her blood, and she can do nothing about it now.
Since she declined to test her 'B' sample, she confirmed basically that she's 'guilty' and it will be counted during the negotiation of the time of her disqualification. After her 'B' sample test she would be 'proved guilty' too. It's not 'at least trying to get the B sample tested', it's more like to choose a lesser from two evils.
Just think about it. It's a rational and logical decision. I absolutely 100% agree with it, and I most probably would do the same in her position.
Because it would be positive too.
1. this rumor about accumulation of the substance is true, scientists will look into that.
2. someone put it in her drink/food
3. there was a mix up or a false positive result at the lab
And she and her team would want to exclude the 3rd possibility (and there have been mix up's and false postive results in labs, not many, but there are cases).
And it's important, because yes, they cannot start at Worlds, so much is clear now, but if they want to continue their career the duration of the ban (if a ban is necessary!) is all important.
If they decide to not try to have the B sample tested they either
found how it got into her system or
they rely on this accumulation of the substance thing (but I think that nothing will come from that ...) or
the Russian Sports Ministry is making a deal with the WADA regarding all those doping cases.