Not sure about this one. On the face of it, it seems reasonable.
However in cycling the offenders always seem to have a plausible answer and its difficult to see the difference between genuine errors and proper cheats. Once you give light sentances (ie less than the two years recommended for drugs cheats) it is a slippery slope.
Frankly a professional sportman. With all the support available at the clubs, should not get caught out like this and, in my view, there should be zero tolerance. Fail a drugs test and you get two years end of.