I see what you're saying SAS and I think it may be that it's a presentation and some of the info may be clarified by the speakers notes. Just a guess on my part. For example in the bullet point directly above the one you quoted they address your concern
Could analysis by date manufactured be accomplished?
– Yes: Feasible, but provides much less valuable information.
– Even if manufactured after 2003,may still have a certification basis date many years (perhaps decades) prior to 2003
Also if you look at the conclusions on pages 10-13 it's broken down based on compliance or non-compliance with 27.952.
I'm guessing the 2003 break has to do with comparing their data to the Taneja & Wiegmann study released in 2003. Otherwise the 2003 date makes no sense since both CFRs referenced in the report took effect before 2003.
Again all just guesses on my part. I knew the presentation was out there so I thought I would add it to the discussion.