I haven't seen a separate photo of the bayonet, but can't help but wonder if there isn't a closer relationship between the 'bayonet,' the 'eye' located behind the cock, the 'bump' in the triggerguard and the trigger.
Could not a piece of leather or twine, threaded through these points and terminated at or pivoting somewhere along this 'bayonet' (which itself pivots/hinges at the bottom of the toe of the butt stock,) permit a 'remote' method of firing this flintlock, while not even holding it?
Intriguing, if not unusual elements to say the least. The sliding cover secured by staples is pretty slick. The other holes... more intriguing yet.