Disable the whole module (don't even finish executing it) on non-shamans and clean up some messes.

MultiCastBar.lua

@@ -2,13 +2,13 @@
 	Copyright (c) 2009, Hendrik "Nevcairiel" Leppkes < h.leppkes at gmail dot com >
 	All rights reserved.
 ]]
-local L = LibStub("AceLocale-3.0"):GetLocale("Bartender4")
+
+if select(2, UnitClass("player")) ~= "SHAMAN" then return end
 
 -- fetch upvalues
+local L = LibStub("AceLocale-3.0"):GetLocale("Bartender4")
 local Bar = Bartender4.Bar.prototype
 
-local table_insert = table.insert
-
 local defaults = { profile = Bartender4:Merge({
 	enabled = true,
 }, Bartender4.Bar.defaults) }
@@ -21,11 +21,7 @@ local MultiCastBar = setmetatable({}, {__index = Bar})
 
 function MultiCastMod:OnInitialize()
 	self.db = Bartender4.db:RegisterNamespace("MultiCast", defaults)
-	if select(2, UnitClass("player")) ~= "SHAMAN" then
-		self:SetEnabledState(false)
-	else
-		self:SetEnabledState(self.db.profile.enabled)
-	end
+	self:SetEnabledState(self.db.profile.enabled)
 end
 
 function MultiCastMod:OnEnable()

Options/MultiCastBar.lua

@@ -2,6 +2,9 @@
 	Copyright (c) 2009, Hendrik "Nevcairiel" Leppkes < h.leppkes at gmail dot com >
 	All rights reserved.
 ]]
+
+if select(2, UnitClass("player")) ~= "SHAMAN" then return end
+
 -- fetch upvalues
 local L = LibStub("AceLocale-3.0"):GetLocale("Bartender4")
 local Bar = Bartender4.Bar.prototype
@@ -39,7 +42,6 @@ function MultiCastMod:SetupOptions()
 			name = L["Totem Bar"],
 			desc = L["Configure the Totem Bar"],
 			childGroups = "tab",
-			disabled = function(info) return select(2, UnitClass("player")) ~= "SHAMAN" end,
 		}
 		Bartender4:RegisterBarOptions("MultiCast", self.options)
 	end