Finicum is face down (you can see the belt buckle). This is the inside left side of his jacket.
Look at the angle of the grip. The grip is away from the jacket button holes, which would mean that the grip was toward his left armpit. This would be very awkward for a person to do. On the other hand however, it would be very easy - natural - for a person to place the gun in the pocket like this once that pocket was turned out as it is here.
What utter BS. He had his own gun in his own pocket - a gun that he reached for twice, as clearly seen on the video.