None of us have direct knowledge of anyone's motives. We can however make reasonable inferences. And what would be your "reasonable inferences" here?
I read the article. I did not find it at all polemical. Why do you?
The entire paper is simply an extended version of the ancient and hoary argument about the Cambian Explosion. No new results, no new analysis. There is a first rate and detailed critique at
'The Panda's Thumb'. Rather than reinvent the wheel, I refer you to it.