Brian,
I think that the same rationale for the ruling with respect to inspection program holds for the interpretation of the term "current" in the regulation. If current means the latest version, they the manufacturers get to mandate the expenditure of funds and compliance with new procedures without any kind of administrative procedure. That same rationale prevents the manufacturers from making a service bulletin truly mandatory. If the manufacturer could just amend the service manual to include the information in the service bulletin, then those service bulletins would become de facto mandatory.
That is my best interpretation, and I am unswayed by the opinion of an FAA mechanic writing in a journal. However, I will concede that there are likely a lot of FAA inspectors who think that current means the latest version.
Of course, I am a lawyer so I can argue both sides.
But better yet, I can defend myself from the fed. I have a 2000 edition of the PA-30 service manual and all the AD's and Service Bulletins. I believe I am in compliance and the FAA is going to have to spend a lot of the taxpayers money if they want to make me a test case.