If you train your gun on someone when they don't have theirs out, or are in a desperate position, Fear RP should be in effect.
I doubt people actually follow this rule however, most would simply panic and begin firing or activate some /comms SOS or beacon.
Your suggestion made in an attempt to remedy this would be unbalanced. Adding the taser to Bounty Hunters loadouts would make them far too overpowered.
Bounty Hunters have incredible load outs and some of the strongest weapons on the server. To give them the taser is to give them the ability to effectively kidnap and disarm anyone on the server with ease.
Additionally, as stated above one of the Bounty Hunters has a taser in their class (Zuckuss).
If you're trying to kidnap someone, enlist his support, or gather enough Bounty Hunters to surround them and cuff them whilst they're unaware of what you're doing.