In short, he argues that it’s no surprise that cutting the brain in half has no effect on abstract thought, and then he argues that delicate complexity and interconnection is essential for abstract thought. Dr. Ali is debating Dr. Ali.
Abstract thought is qualitatively different from concrete thought. To understand this, consider a chiliagon. A chiliagon is a closed regular polygon with 1000 sides. It is very simple to understand abstractly. However, it cannot be imagined concretely