I have a boltsnap tied to my octopus with cave line. When clipped onto my BP/W, it hangs close enough that if I lose my primary, for whatever reason, I can duck my head down, and grab my octo with my mouth. It's secure, eminently deployable, and streamlined.
That's fine for you, but the issue is not being able to get it unsnapped and deployed in a a timely manner for another diver who presents OOG. If the boltsnap jams or otherwise doesn't deploy, you're going to have, at best, that OOG diver about 3" from you all the way to the surface.