I did not recall GL criticizing Noonan’s Dakar planning so I went back and re-read it. I still do not see anything in there critical of Noonan’s methods. GL goes so far as to say that the Dakar planning was used as an example in AFM 51-40. He does have some fairly harsh words for AE who was not a navigator but none for Noonan.
Perhaps you are referring to GLs text regarding the shift in destination to St. Louis, Senegal, with there being few notes on the chart? That sounds to me like it was a case of changing the destination on the fly based on decisions that were made based on requirements that we do not know about. It does sound very much like they hit the African coast fairly closely to where Noonan expected them to.
Looking at Noonan’s planning and in-flight execution, it seemed to follow a lot of best practices of the time.
GL’s comment about “But from this point Noonan’s navigation becomes strange” does not appear to be a reference to Noonan suddenly getting sloppy but, rather, lack of notation on the chart that the destination changed.
I’m guessing here but I know that GL carries Noonan in high esteem.