In the released indictment [2] (Apparently there seems to be a superseding indictment), DPR was charged on four counts. Count one is "Narcotics Trafficking Conspiracy", none of the counts are "Murder-For-Hire". But, there are three overt (motivating) acts for the "Narcotics Trafficking Conspiracy": a) Provide a platform for selling drugs b) Solicit a murder-for-hire c) Logging in as admin on Silk Road
So, while the charge "Murder-For-Hire" probably seems hard to prove (as stated above), using the intent of it to justify the count "Narcotics Trafficking Conspiracy" worked here. In a sense, I believe, DPR can not be labeled officially with "murder-for-hire", but in order to protect his "Continuing Criminal Enterprise" and as such commit "Narcotics Trafficking Conspiracy" it appears that he would have committed a "murder-for-hire" crime.
Sources:
[1] https://www.springsteadbartish.com/federal-criminal-defense-...
[2] https://www.justice.gov/sites/default/files/usao-sdny/legacy...