A response to your first thoughts
I responded the same way you did when I read the sentence about grad school. While you are reflecting on these points from the art instructor point-of-view, I am looking at this book through the lens of an instructional designer. While it might seem strange at first, there is actually quite a bit of overlap! When I design tools for work, I have to start by identifying a goal, but then there is a creative process during the brain-storming phase that requires the ability to use both sides of the brain, first from the creative right lobe inventing ideas, then from the left lobe as I think critically about how it would be adopted, the type of experience students would have, or even how it fits within a specific pedagogical context. Additionally, I have to switch back and forth as I reflect on each of these points. When I imagine a students experience with the content, resource, or tool I am considering, I have to invent scenarios that again demand the creativity only the right lobe could lend.
As a small anecdote, I was removing the stitches in the hemmed sleeve of a sweater today. After I snipped the thread, I was alternating index fingers as I pulled each thread out, much the same way you would unlace a shoe. I immediately considered the test subjects of chapter three that had their Corpus Callosum bisected, and how much trouble they would have with that activity being that their hands were operating independently!