Is this allowed?

I doubt that anyone can enforce the "rule." It's allowed to be written but always ignored. Private/group giveaway rules must be approved beforehand, and even then this so called rule would never be approved. None of entrants of the giveaway is bound to try to accommodate the giveaway creator and mark the gift as received immediately if he/she doesn't feel like waiting online just for the minute chance that he/she might win one of the many giveaways entered, though they must mark the gift as received within 7 days of the end of the giveaway if they received the game.

Sounds like more of a request than rule.

Well... Having your face, I really wouldn't give a fuck. I would just give you as many presents you want :P