I was thinking, since discipline still has no abillity to free themselves from Crippling Poison and Holy having the Poison dispell (wtf) I was thinking we might want to have a talent (or adjust one) which would make the bubble act as some sort of immunity shield for "chance-on-hits". The chance on hits would only count for melee hits ofcourse. This also does mean it can stop Enhancement shamans from getting WF procs but luckily for them they have Purge.
With the amount of magic dispells ingame atm I see this as a better solution towards the problem then to give Holy a poison dispell which is useless since Discipline is still the PvP build. PW:S would only grant immunity to them while it's active and would not remove existing effects when cast.
Ofcourse it could be turned into something which would free the caster from all movement impairing effects but I don't see how that would improve the situation.