It would be a mistake to see Deleuze and Guattari’s WHAT IS PHILOSOPHY? as to any significant degree devoted to engaging with Laruelle’s work.
There are only two mentions of Laruelle, and they are contained in footnotes.Both reject his scientism. WHAT IS PHILOSOPHY? develops Deleuze and Guattari’s own concept of non-philosophy, reprising the theme of the image of thought that they had developed over two decades of collaboration. They see Laruelle’s notion of non-philosophy as a scientistic double of their own.
The last two sentences of WHAT IS PHILOSOPHY? are devoted to a critique of Laruelle’s scientism: « François Laruelle proposes an understanding of non-philosophy as « real (of) science, » beyond the object of knowledge…But we do not see why this real of science is not also non-science ».
Their only other mention of Laruelle in WHAT IS PHILOSOPHY? is also consigned to a footnote, and it again critiques his scientism: « François Laruelle is engaged in one of the most interesting undertakings of contemporary philosophy. He invokes a One-All that he qualifies as « nonphilosophical » and, oddly, as « scientific, » on which the « philosophical decision » takes root ».
In PRINCIPLES OF NON-PHILOSOPHY (published in French in 1996, the year after his « reply » to Deleuze) Laruelle critiques his earlier position as scientistic, but without even citing Deleuze and Guattari.