At this time, you can't use the test for plasticizers as proof of doping, so that's not really relevant.

Contador is subject to the Spanish cycling federation, Fuyu is subject to China's. The rulings are not required to harmonize, as long as they fall within the WADA guidelines.

Unfortunately, since cheating is rampant, masking agents are commonly used, and many cyclists of all levels of ability will do anything possible to gain an edge, the rules need to be exceedingly strict. Accept the "contamination" from one cyclist, even with good reason, and voila you've practically taken the substance off the banned list.