AFAIK, it wasn't done because he wants to be lenient on drug traffickers, but because the overall case of Ross Ulbricht is huge in certain political circles that he was pandering to during the presidential race, so seems he's "paying back" for those votes or something.
> “Ross Ulbricht has been a libertarian political prisoner for more than a decade,” said a statement from Libertarian National Committee Chair Angela McArdle. “I’m proud to say that saving his life has been one of our top priorities and that has finally paid off.”
Seems the US-version of libertarians is that group.
