Any number of things could cock that hammer besides an intentional thumb move--I'll pass.
I really don't follow you there Tracker with my 40 + years of experience with Derringers.
I was always fascinated with them as a kid and got my first German one in 22 when I was 14, I was shooting my Dad's when I was 7 or 8.
I have and have had the cheap Italian ones and have a good Italian one, have some good German ones. I got rid of all of my American Derringers because the Bonds are far superior in every aspect. As I mentioned before I shoot them in competion and they have the mainspring lightened and still no accidental cocking.
The hammers take intentional force to cock. Trust me, you can't accidently cock them. They take more force than on a Smith or Colt. Given that, why carry a external hammered revolver?
When I was young and dumb I used to carry a German 38 loose in my pocket with no issues. Now don't get me wrong, I am not advocating carrying a Derringer for CCW. There are much better choices. But if one just has to carry one, at least pick one with a trigger gaurd like the Bond or the Double Tap. And the scales tip even further towards the Double Tap by being hammerless just as a "bump" factor or fumble factor. And by being light. The Bonds are heavy for a small gun.