OK perhaps you are right, but I'll provide you with a quote from Mike Fullers blog anyway:

 

"Porsche approached IMSA about a variance to the fuel regulation as they struggled with a technical detail on their direct injection RS Spyder engine.  Apparently the spec E10 fuel was causing detrimental levels of deposits to build up in the direct injectors leading to reliability concerns.  IMSA issued the variance to allow Porsche (and any ALMS team) to run higher levels of Techron in the IMSA E10 fuel".