You really need remedial English, they said that Xbox would get the game 30 days before everyone else, so unless they take the files away from the xbox users, they have content that we don't have for more than 30 days, so the exclusive use of this content is going to be longer than 30 days. In order to comply with their 30 days exclusivity they must release the DLC to PC and PS3 players 30 days after they released it to xbox players, other wise they are in breach of contract.
That's a question of who has the contract; which parties are involved.
The two parties involved are Microsoft and Bethesda, and thus, the only ones bound by it. In this case, Bethesda has all the power and the agreement was simply to give Microsoft 30 day exclusivity for the Xbox 360. Microsoft got that, and thus the contract has not been breached in anyway whatsoever.
We are not a part of the contract and thus have no say. It's also not false advertising because false advertising is for when you bought a product under false pretences, where the seller deliberately fooled you to make a sale. We've neither bought a product under false pretenses nor have they deliberately fooled us.