Well, I don't have a facebook account, but if I had, I'll click this "Like" button anytime. Because unlike those who complains in a knee-jerk reaction I actually know how to read, and when I do read an article, I read it until the end.
first, they already gave money. Maybe they should have said it clearly, but someone would still have been "outraged" at how they use the tragedy to "brag" about how charitable they are.
second, this money they pledge to give as a bonus for "Like", I don't think they have it just lying around. Remember, they already gave what they could spare. It's money they would have had to spend on advertissement later, that they could spare only if they found another way of raising awareness about themselves in a cost-free way. Such as this pledge.
So, this "outrage" is about a company which already gave what they could, and dared ask people to help them lower their advertisment cost so they could spare some more to give.