The strip sander does have one accessory which is for sharpening. It allows you to guide lathe tools through the sharpening and honing steps. It's a bit hard to see in the second photo, but note that when this accessory is mounted on the strip sander that it then must run in reverse. That means that you are driving it with the quill side of the Mark V not the SPT hub on the back side. Imagine yourself in the middle of some spindle turning when you realize that you need to sharpen your skew. Now you must remove your work, your spur drive center and your tailstock. Mount your new drive hub, your strip sander (which hopefully have the sharpening jig in place) and sharpen your skew. Now, reverse that and you're ready to go again. Oops! You dropped your skew! Do you get my drift? I'd pass on this one.
Here's a video showing the Shopsmith Strip Sander being used for sharpening Plane Irons