To be able to sue legitimately for copyright infringement, Righthaven must have had some substantial right under copyright assigned to it - that is, something beyond the bare right to sue (Silvers v. Sony Pictures).
Here, the agreement truly provides for a sham form of assignment: (1) Righthaven is expressly said to have no rights to exploit any of the copyrights purportedly assigned and all such rights are reserved to Stephens; (2) Stephens can block Righthaven from suing any particular party; (3) Stephens can demand the copyright back at any time; (4) Stephens gets a 50% cut of any recovery in any lawsuit filed; and (5) a Stephens-controlled representative is required to be part of Righthaven's key team. Given these terms and conditions, Righthaven is basically a puppet and Stephens is what the law calls the "real party in interest" in these lawsuits. Since no true assignment took place, the current lawsuits filed pursuant to this agreement are in deep trouble. And, just in case the Righthaven lawyers missed it, the judge who is responsible for handling these cases is hopping mad at them.
The bad news: if such assignments are done as true assignments, the Righthaven model still works, or at least is not undone be a congenital defect that can't be overcome in future cases.
Kudos to EFF for splendid work in pounding through the fake exterior of these cases and sending them to perdition, for that is surely where they will land after this revelation.