If I remember correctly, there were comments from both the prosecution and judge that would basically prove that point- and they allowed evidence related to those other crimes in the trial. If they could prove this misconduct, they may even be able to argue double jeopardy.
The judge said during sentencing that she was giving Ulbricht an incredibly harsh sentence to make an example of him to others who think that facilitating selling drugs is a victimless crime, and she was also angry at the huge stack of nice letters that people sent to the court in support of Ulbricht.