But I should have added, chewing is the first part of the digestive process, so eating solid food without chewing it makes it hard or impossible to fully digest.
Steel cut oats are partially cooked so they can be cut, but eating them uncooked will make them impossible to digest. At best, they're passing through, worthless, at worst, they're getting stuck somewhere. Why would you want to eat partially raw oats? If you want the fiber, put oat bran in your shake. Not nutritional value, but it will provide soluble fiber that helps with cholesterol. If you want to be able to digest the oats, cook them and eat them -- probably much more nutritious than what's in your shake, if it's a high sugar or synthetic sugar protein shake. For even more nutrition, cook whole oats -- they have all the nutrients of oats, but they take a long time to cook. If you insist on eating something chewy in your shake, use rolled oats, and roast them to complete the cooking process.
It surely doesn't matter that much. I am all for healthy eating, but...