4E power fluff is not the place to go for rules issues. If that were true, Warlords could only Inspiring Word on conscious non-deaf allies.
This isn't a 'Fourth Edition' conceit. This is a general conceit with any character you create in any roleplaying game ever. The players have a responsibility to create characters that make some semblance of sense relative to the world they are in. The fact the book they pull the rules from say 'Dungeons and Dragons' on it does not in any way exempt them from this responsibility.
Also in 4E clerics are empowered by the church and not a god directly, so "pacifism" is more a worldly concept. Nothing stops you from being a pacifist cleric of Kord that refuses to wound enemies he after he has drawn first blood.
Except for the fact that the empowerment IS by the church, which implies some sort of lip service to the ethos of said belief system. Now, you could justify the clerics of Pelor giving some one the power to heal better at the cost of being less able to bring suffering to those near death. You could see Ilmater's clerics doing that. But could you then see said clerics investing the -same- initiate with the power to summon weapons and magics that are designed inherently to brain people to death?
Particualarily when such ethos have access to non-damaging methods of combating enemies of the church?
You have two options: Either the divine aspect of the diety gave the power to the adherant, or the church that espouses that diety's ideals gave the power to the adherant. Either way, it results in the same basic premise: Someone granted that adherant the power, and that someone did so on the basis of the ethos that someone wishes to espouse.
Kord, being a god of war, and of storms, doesn't exactly have an ethos devoted to simultaneously healing the wounded, granting succor to the downtrodden, AND summoning implements of destruction at the same time. The two are antithetical.
I'm not saying it's impossible to explain, but the fact is... you need a little better than 'OH A GOD DID NOT DO IT SO IT TOTALLY WORKS.' It's not even restricted to arcane characters... every single pip and dot on your character sheet for every character ever should have some sort of rational explanation, and if there are inconsistancies, or even contradictions, you need a LOT more of an explanation than 'The rules don't say I can't.'*
The DM is the arbiter, and -can- say 'This is stupid, try again, sir.'
My groups pacifist cleric also carries a mace. That's a weapon, and he's supposed to be a "pacifist" (which in game terms doesn't mean he can't hurt others, but that he is forbade to himself kill.)
There actually is a difference between carrying a mace, and using the same font of divine power to summon a mystical weapon as a manifestation of your diety's puissance.
So would your force a pacifist cleric to not use a weapon at all? Or any damaging prayers?
In the former, no. Again, he's carrying the weapon, and a weapon can be used defensively, to parry blows, and such. However, if he has a power that summons weapons, he has to be able to explain how he is simultaneously summoning divine power that heals AND punishes him for using violent powers, and using that -exact same power- to create implements of war.
That puts the onus on him to come up with a plausible explanation. This is not the same as forbidding that character, do not mistake me. But he had better have some sort of explanation other than 'It gives combat advantage.' Some characters are easier to explain than others; the fighter with axe-based attacks who takes weapon focus: axe doesn't need to state one because the explanation here is obvious: He's an axe-specialist. Go team.
Imagine instead if a sorcerer took a feat that said 'If you use a fire power, you take 5 points of damage' as a negative aspect. Then he takes an ability that is a fire power. I think some explanation is in order here.
The argument that a summoned Spiritual Weapon somehow breaks that concept of pacifism more than a +2 Lullaby Mace or a Lance of Faith doesn't hold any water.
1) Pacifist Clerics generally use implement powers in their builds
2) The cleric is not using his divine font of power to create these things. He is using it to undo wounds.
More over, there are ways available to a cleric to force combat advantage, through prayers, that don't involve conjuring a spiritual weapon. It's not like 'This is the way to do this effect I want' is even a valid argument.
*as an example, a cleric of the Raven Queen could belong to a mystery cult that states that her clerics are endowed with the abilities to represent her whim... as fate is dualistic, and as agents of her will can stave off death from those who are fated for other things, while using a summoned scythe as a symbol of her glory.