The only time that watchman spec works for PVP is Voidstar defense. Rage and carnage are better than watchman for every single warzone, by a longshot.
Hence why I said "situationally viable". Though, as pointed out earlier it is wonderful for dueling, which is PvP but not necessarily a relevant part, albeit. I just worry buffing any of the specs too much in any way will bring the eventual nerf-hammer down upon us thus ruining the near-perfect balance we currently have.