Fear of Putin?
<<Concerning the Russian whistle-blower couple, it's sad to think that whether it will be this year, next year, or the year after that, Putin and his thugs have long, long memories.>> Gray
If you consider the side of Putin that is in actuality a clean-living sportsman, it is very likely that he would be on the side of clean sport and therefore unlikely to hold any grudge against Stepanova.
While the power axis certainly exists in Russia, it doesn't obey its own laws with any comfortable consistency, and it is entirely possible that the elements who promoted the doping did so on their own initiative. It is paradoxically this independence of movement that demands the presence of a strong ruler like Putin to keep the loose cannons under control, except when it is convenient no to. Sorry if this is offensive to traditional Western political perspectives.
One example from a few years ago was a near shootout between the Interior forces and the Federal Narcotics Bureau resulting from corruption and a conflict of interests. Putin had to dissolve the narcotics arm and incorporate it into the other body if I recall correctly. (Closest I can find: http://www.sovsekretno.ru/articles/id/4633/ ). They were completely acting like children with guns and power and Putin had to end the histrionics.
So maybe he had nothing at all to do with the dopings (especially as it would go against his personal ethics), and that it was a bunch of low-life bureaucrat cheaters that organised the whole thing after attending a weekend team-building exercise that emphasised "empowerment" and "self-determination" and so on .
But I could be mistaken.