I can't find any announcement that says how much of the purchase price of the llama is going to charity. If I'm buying something I normally wouldn't buy because the purchase is helping people, I'd like to know how much help they're getting.
Without naming names, another game company that has a similar promotion for the Red Cross is donating the entire purchase price of their in-game pet and they say that up-front.
This is important because there there are a ton of charity scammers in the world who solicit donations for charity or disaster relief who make a 5% donation and keep the other 95% of the money donated. I'm not suggesting that KI would do something despicable like that, but when there's no information about what to expect, there's no way to know whether my donation is being used in a way I think is worth supporting.
The llama is just frosting on the cake. The donation is theoretically the important part of the equation; otherwise I might not be spending the crowns on a mount I don't really need.