It absolutely is not. His viewpoint is C, which begins, "Appropriate physical action of the brain evokes awareness". How could he be more explicitly materialist? Furthermore, Penrose is quite clear in stating that he "shall maintain that this ingredient is itself something that is not beyond science -- although, no doubt, it is an appropriately expanded scientific world-view that we shall need ". In other words, he thinks that physical material is fully up to the task; it is only our understanding of material that (currently and correctably) falls short. We don't know everything, but materialism isn't about what we do or do not know; it's about how things work.
Physicist: It absolutely is not ... In other words ... We don't know everything, but materialism isn't about what we do or do not know; it's about how things work.
Sorry, Physicist. It absolutely is, and Penrose's words speak for themselves. Materialism is a limited and incomplete description of how some things work. There is a huge void in our scientific knowledge. I applaud Penrose's candor and believe that his efforts, and those of others of like mind, will bear fruit.