Go play sim city
This whole idea is about as pansy as it gets. While we're at it, why don't we just stop dueling altogether.
If this idea is implemented, you will be taking away a big part of the game. Duelers duel for many reasons. Some being xp, money, stats, war, or just to keep the motivation down.
Everyone has to earn money somehow. Some work jobs, some do quests, and others challenge them to a duel to steal their hard earned money. If dueling is a player's primary source of income, that would be like making it where a worker could not get money from doing jobs, or a quester whose questing was limited.
However another reason players duel is to lower the hp of hp tanks before a fort fight. A fort fighter tank could use this feature to protect himself from duelers of the enemy side. This would take out a strategic action of the game away.
By building your character in a manner that does not give him benefits in duels, you are aware of what you are taking on. And furthermore, by joining a town with such a character, you know the dangers that you face.
There is a solution for a nondueling character build residing in a town. They may place a bounty on any dueler who attacks them. By placing a wanted dead bounty, the player will have a bounty over his head and many players will attempt to attack him.
In addition to placing a bounty over the dueler's head, ask for help from your town mates.
I believe your idea is not something that will add to the overall goodness of the west. It would actually hurt the west, by nerfing the amount of players that a duelist can fight. If you want to play a non pvp game, try sim city or farmville.