Here is my guess on this strange but true claim..... Is it possible that HD discontinued the item? Yes, it may be a simple part number error or change,. I have found that part number changes often take 4-6 months to reach dealer memos and are not updated until the yearly catalog changes are made.
Remember..... after appx 2007, the number of baggers that went out the factory door with cruise control sharply increased. Was this to justify a higher price tag? Perhaps, but my guess is that it was part of the re-design headed for the 2009 touring models. The frame changed and so did a number of factory options. Kind of a chance to "re-invent" the new model year.
I installed the cruise control on my 07 bagger with no problems at all and it only took about an hour and 20 minutes or so. Perhaps HD was looking to capitalize on the dealer install time in order to increase profits but failed to notify dealers in a timely manor. It has happened mant times in the past and I'd bet this is just another addition to "Factory techincal glitches"
I doubt this post helps, but it may provide some insight as to where it is rooted.