Well, a lot of it likely extends from his past attempts.
20 years ago, 2002, he put out A New Kind of Science with great fanfare. And it was a very good text on his ideas involving cellular automata and outlaying his patterns.
But it didn’t ‘take’ because he wanted to replace rather than work with existing systems. There’s certainly ways to incorporate both together; a wholesale replacement is not required; He’d had a bit of a chip on his shoulder about it; and I mean, his work is fantastic and he deserves that chip, but it had an air about it that wasn’t necessary.
So, when he came out with something more thorough, the memories of A New Kind of Science remain strong and recent enough for a lot of physicists that remember A new Kind of Science saw _A Project to Find the Fundamental Theory of Physics_ and had a strong case of “oh no not again”