The murder-for-hire scheme was in fact charged conduct, was introduced at trial, was rebuttable by the defense, and he was found guilty of the associated charge.
Here's the indictment: https://www.justice.gov/sites/default/files/usao-sdny/legacy...
Page 5 of the indictment includes the murder-for-hire activity as part of the first count ("Narcotics trafficking conspiracy"). Ulbricht was convicted on this count of the indictment.
Here is Ulbricht's appeal against sentence to the Second Circuit Court of Appeals: https://caselaw.findlaw.com/us-2nd-circuit/1862572.html
Ulbricht doesn't even bother arguing that the court was wrong in considering the murder-for-hire during sentencing, only that they shouldn't merit a life sentence because they probably didn't actually take place.
https://caselaw.findlaw.com/us-2nd-circuit/1862572.html#foot...
Later
I removed ", and bets more of the case on it.", to dial it back a little.
What you're doing here is presenting the indictment with the murder-for-hire as overt acts and relying on the sleight of hand that the reader will assume the conviction asserts the overt acts, when in fact the conviction only generally relies on at least one overt act (and need not be any murder-for-hire related one).