AnaNikolaj: The fairest thing for the Showdown would actually be, if the losing player would need to putt out the last hole as well, but they didn't programme coin games that way.
If a losing player (who was not playing in the Showdown) were forced to putt out, it's very likely that that player would just force-close the app, thus causing the Showdown Bogey Glitch or the Showdown Replay 3 Holes Glitch for the other (winning) player.
The best thing for WGT to do would be to just move the Showdowns out of the coin rooms altogether. Especially since they apparently don't have the talent to fix the glitches caused by the Showdowns being played in the coin rooms.