My bad.
There are two works by Dabadie-Salles. The work that Haar said had not been well received in the scholarly community was his 1969 work arguing Simon Magus was the author of the Great Pronouncement/Revelation.
Translating Salle's earlier article that I originally referred to, in the opening paragraph:
Since the work of Waitz, critics have unanimously agreed, with a few nuances, that the character of Simon in the Clementine Novel is an arbitrary and fanciful creation of the compiler (for the novel is in reality a vast compilation of very diverse sources) 3, and that the adversary referred to under this assumed name is not the modest and mythical Magician, but an heretic of quite different importance, Marcion. From this it is concluded that the Clementine novel could only have been composed in the third century.
The footnote in Salles refers to the work by Waitz and also lists a small bibliography of Waitz's critics.
Turning to Waitz -- it's online at
https://archive.org/details/texteundunt ... ew=theater -- one finds what is apparently the early case for chapters being added to the Clementine novel to attack Marcion through Simon Magus.
It looks like Simone Pétrement's reference to Simon Magus being a cipher for Marcion was a reference to a view from earlier times -- though I don't know how prevalent the view still is that Marcionism is a target of some of the Clementine novel. But the question is not important enough for me to plough through machine translated German of various articles to be totally in the picture.
LC -- it looks like Waitz was arguing for different versions of Clementine literature across centuries -- pre and post Nicene. But you have the links if you want to chase it up.