I don't think he did. The guy who he allegedly ordered a hit on doesn't believe it and argued for Ross's release.
Reminds me of some story where a woman petitioned for the killer of her relative to be released, and after release the killer killed that woman.
This might be a case of conflict of interest though, as saying instead that Ulbricht did ask him to kill someone could worsen the legal position of the alleged hitman as well, depending on the specific circumstances of the case.