Why would Twitter do that? They have sent their money by their own greedy decision. It is like asking for a compensation from a food manufacturer, when you dont like how restaurant prepared your meal. No one forced people to send money. When you see an ad on TV-shop saying "Buy this product, it has a discount only today!", do you immediately pick up a phone to make an order?
Where in the world, when the meal comes in a bad way, you can't get a refund or a compensation? If you find a strand of hair in your soup, you can ask for a refund (or at least a dessert). But yes, there will be no compensation, even though your comparison doesn't make too much sense. 
Yes, you could ask for a compensation, from a restaurant (twitter account, which posted fake giveaway tweet - in our case), but not from a farmer, that delivered vegetables to the restaurant (twitter company as it self).
What twitter can do? Refund sent funds ? But how to prove a connection between twitter account and btc address (if only ask to sign a message).
I dont think thats greed, people tends to like some giveaway in any means.
"If you send me 1 bitcoin, I will send you 2 bitcoins back" - isnt participating in this kind of a trade may be considered as an act of greed?
. 
