There's a great write up here by u/djiti-djiti that goes into a lot of depth about the claims made in Dark Emu. The bottom line is that a lot of the seemingly controversial claims made in the book are not actually particularly controversial in a scholarly sense, and Pascoe is not really making a groundbreaking new case so much as drawing upon decades of existing research. The book has its flaws and limitations to be sure (which are also covered in the linked post), but the backlash it has received is far out of proportion to them.