The Scripture Is False And The Biblical God Is Dead.

[The Grand Nudger]

It's important to point out that ast isn't illusionism, or..at least, that's not what they're proposing. It's critics express frustration that it doesn't make this claim. An illusion, as ast proponents would describe one, would be something like a phantom limb. A correctly functioning internal model is not, however, taken by them or generally to be an illusion.

Michael Graziono had this to say on the matter after elaborating specifically on the above -

Using the term “illusion” in that more inclusive sense makes a philosophical point, but I prefer not to use the word in that way. That philosophical emphasis paints a picture in which the arm schema is a separate entity unmoored to reality, a construct of the brain, a way the brain tricks itself. But the arm schema is anchored to reality and has a specific functional purpose: to represent the arm. When it is doing its job effectively, it is not well described as an illusion. It’s a model. It’s a representation. It’s the brain’s useful caricature of the arm. Given the constraints on the brain’s processing ability, it is necessarily always true that what we think we have and say we have is a distortion or simplification of what we actually have.

I can see why dennet would want it to be an illusion, and I could see why dualists would want it to be an illusion - but that's not what they have in mind.
(I'll let myself out)