A deadly Catch 22? It is possible to execute a person with ID/MR in the United States--Time for SCOTUS to revisit Atkins?

As a non-lawyer and a professional who deals primarily with science, logic, and fact, I am at a lost for words re: the decision, two days ago (Webster v US, 2010), that a person with clear evidence of MR/ID (as admitted by one of the ruling judges), must be executed because of some kind of legal mumbo jumbo.....under federal habeas corpus (HC) statutes dealing with successive HC claims based on new and material evidence, one must prove innocence to be spared from the execution...even if there is clear an convincing new evidence that the person is ID/MR.  Come again?  Say what?  A deadly Catch-22?

I urge interested readers to read the concurring opinion of Judge Wiener (starting on page 6) who states (emphasis added by ICDP blogmaster):

I write separately to emphasize the absurdity of its Kafkaesque result: Because Webster seeks to demonstrate only that he is constitutionally ineligible for the death penalty — and not that he is factually innocent of the crime — we must sanction his execution.

If the evidence that Webster attempts to introduce here were ever presented to a judge or jury for consideration on the merits, it is virtually guaranteed that he would be found to be mentally retarded.

I continue to harbor a deep and unsettling conviction that, albeit under Congress’s instruction which ties our judicial hands so illogically, we today have no choice but to condone just such an unconstitutional punishment.

Speechless. 

Should this be the case that requires SCOTUS to revisit the can-of-worms left in the wake pf SCOTUS's lack of specificity in Atkins?  Should this case not be appealed to SCOTUS?