I own one of his X-Proto lab tiny scopes, which I like very much. From the video, the "watch" scope looks to share the same command set and functionality. The X-Proto is in the form-factor of a development board, so everything is exposed.
On the one hand, I agree with some of the concerns about having your project essentially tethered to your wrist. Just because you can build something, doesn't mean you should.
On the other hand, The little scope doesn't really replace a conventional desktop scope, but it's incredibly handy to have around. Wearing it will keep it close by if you need it. It helps keep the clutter off of a desk and it gives it a solid base, keeping it from sliding around the bench. The X-Proto is so small that it's easily overpowered by the wires attached to it. I pretty much find it necessary to keep it in a solderless breadboard. Wearing it would mitigate that issue.
Also, it reminds me of the calculator watches I used to wear - but much cooler. I'm leaning toward thinking it's positive attributes outweigh the negatives.