User blog comment:Arbington/ME3 Theories/@comment-730941-20100702150142

Also keep in mind regarding the Kasumi DLC that it's a paid download and not every player would have access to it, or bought it. They simply wouldn't hinge an important part of ME3 on decisions made in a quest that wasn't available/wasn't done by all players.

If anything, the greybox decision will be mentioned in an email, maybe dialogue. That's it.