The source of the confusion may originate with the manufacturer and not Wilhelm (albeit, an independent lab should probably double check any claims being made by the manufacturer whenever possible).
When Canson first got into the fine art digital media game, its entire line was indeed OBA free, and Canson proudly boasted about it... often and with gusto. That may be the source of the confusion in the minds of current Canson customers and at Wilhelm Imaging Research. Since then, Canson Baryta Photographique as well as other Canson photo media (e.g., Photo HighGloss Premium RC, PhotoGloss Premium RC, and Photo Satin Premium RC) have been added to Canson's lineup. These media do contain OBAs. But you don't have to take mine or anyone else's word for it. Just train a backlight (available at any hardware store) on the paper in question and if OBA is present it will plainly fluoresce, the magnitude of that fluorescence being roughly correlated with the amount of OBA in the media. OBA-free papers do not flouresce under the backlight.
Of greater interest (and concern) to me in the cited Wilhelm report is that Baryta Photographique and Platine Fiber Rag are now listed twice. The second listing states "(Improved)
" and "now in test" so no results yet. Unfortunately, what got improved is not stated. Is this a reformulation of these products with new chemical/physical permanence properties that printmakers using this product are likely to encounter if they have old stock versus new stock, or is Wilhelm referring to an "improved testing protocol" or retest of the same formula because Canson perhaps didn't like the somewhat lower scores Wilhelm originally published for those two media?
I note, for example, that Epson's Digigraphie certification program has opened up to third party media such as Hahnemuhle and Canson, but there is a 60 year print longevity specification that must be met. Go figure that a high OBA paper with poor media whitepoint stability like Epson Traditional Photo paper (Exhibition Fiber paper here in the U.S) manages to jump that 60 year rating hurdle using the defacto industry light fade test methods, but the Canson Baryta Photographique and the Canson Platine are not elligible for inclusion in the Digigraphie program according to the published Wilhelm results.
Inquiring minds want to know