He is not wrong, you are. It is impossible that they are selling out for making a FREE, little game for facebook. They are not getting paid for it, people doesn't have to pay to play... and it's not like they need to promote themselves this way to be more famous. They CAN'T be more famous than they already are. It's just a funny way of promoting the albums and leak a new song.
Some of you have a really misleading concept of "selling out". I will make it clear:
Changing radically their music style (to electronic music or dubstep, for example) to reach other fans ? --> Selling out
Making a mini-game to give fans the oportunity to listen a new song and have fun --> not selling out
And don't tell me GD changed radically their music because they don't. Obviously there is an evolution through the albums, and they have changed, but you can fell they are the same. It's not like Muse, who now are doing dubstep and electronic shit.
It's easy to get if you are not a dumb I-only-listen-to-underground-music-because-unknown-means-better.
Dammit, it's fucking angry birds, it's just to have fun, which is the purpose of this whole trilogy. But if you can't understand that, obviously you won't like it...