If 12 was at his wrist and 6 was at his forearm, then he could turn his wrist and see the time correctly.
If this is the case, then that watch reads 10:10.
Put on a watch and try it.
The watch reads about 3:40, which was the actual time.
You wear the watch on the inside to avoid glare from it when sighting. This guy has had training, that was evident throughout. The question is why he shot, as he didn’t appear to have a reason.