I think it's because shaving can be meditation too. Putting a lot of attention into any movement can free your mind to wander. Running is like this. Cycling is like this. And I imagine this is true of other activities that are rhythmic in nature like kayaking, rowing, and in-line skating.
Swimming is a great form of moving meditation because it is so repetitive and isolating.
You are pulled inside your head and forced to wrangle with your consciousness. This is fertile ground for new ideas. N ew ideas are important when problem solving in the business or scientific world. They are important while sculpting, writing, finger painting, teaching and healing. Staring at the same problem with stale eyes won't yield much.