sim it
/10char
Just by checking warcraftlogs I can see that the top outlaw rogues went with mantle+gloves. It's not rocket science to assume that any legendary which helps to increase your aoe dmg will be the go to choice.
This statements just proves that you have little knowledge about rogues. With proper legendaries and preparation you can do very strong aoe bursts while also doing a very strong single target dmg. I understand that outlaw is one of the worst spec for this fight (like on every other fight..) but even than a good outlaw rogue's contribution is not something that can be overlooked.