Wait, i always belived that refusing to test the B sample means that the athlete admits his positive?
I can't believe that stonewalling is possible
In the case where an A-sample is positive for something on the banned list, then a rider will be provisionally suspended upon the positive. It requires a positive A+B test to suspend somebody outright, though a rider can spend over a year on the 'provisionally suspended' list in complicated cases (see Serrano and de Bonis on the first biopassport cases). Because a rider is provisionally suspended upon the A-sample testing positive, then what do they have to lose from asking for the B-sample to be tested? If it's -ve they have a chance to clear their name, if it's +ve it's not exactly a surprise. If a rider doesn't ask for the B-sample to be tested, then yes, it's actually a tacit admission of guilt.
However, this case is a bit different. The A-sample is positive, but not for something that's on the banned list - but it's something that apparently only shows up in transfusion. Because it isn't something that's banned, they cannot provisionally suspend somebody on that alone - hence why Mosquera and Garçia are free to ride, and Sevilla's provisional suspension has been revoked. In which case, asking for the B-sample to be tested actually DOES have something to lose, because a B-sample also being positive entitles the UCI to open up disciplinary proceedings. Refusing the testing of the B-sample here may still be a tacit admission of guilt (it would certainly seem so) but may buy a bit of time - if Eze can hold off a suspension for a year or two he can take retirement with it.