I haven't read that, but I've argued against metaphysical idealism. There's also Philipp Mainlander's version.

The word "illusory" is slippery in this context because it can refer to constructs which are real enough, but not "ultimately" or "fundamentally" real. If there are levels of reality and of causal powers, the "illusion" of a self would be as real as anything else made of matter.