Intriguing.
Keeping your one CCW pistol in an ankle holster? Meh... you could have some solution closer to hand? Ok it might be better if you are carrying in Maryland of NYC and you don't have any permit but decided to risk it and carry anyway.
But keeping your first aid kit there? That's an idea. You ran out of real estate on your belt with your holster and spare mag, a pants pocket has your carry knife. Hell you might have a BUG gun in a pocket holster in the other pocket....
But keeping your trauma bandage, touriquet, and kwik-clot on an ankle pouch might be just the thing. Lighter than most pistols, too.