As for the Op's question, yes it is viable in some specs of arena due to how hard you can lock down a caster (assuming your partner keeps them perma snared).
However blizzard executive designers like GC, kalgan, Tiggole & Furor have never wanted any other spec then holy to be truely pvp viable as far as paladins are concerned & assuming they can ever find a way to nerf it for pvp without screwing up the tanking aspect of prot rest assured they will.
(I just wish they would apply the same logic to other classes but I guess its what we can expect given the history they had when they played everquest)