I have a feeling about why Alliance chose LGD.cn.
I think that Alliance don't want to face LGD later on in the tournament. Since they're in the winner's bracket, the only way to ensure this is for LGD to lose early, knock them into the lower bracket, and let the lower bracket teams (and the other knocked down UB teams) try knock LGD out early.
At the same time, Alliance feel they're the only team that have a reasonably high chance of beating LGD. I think they feel that the other UB teams haven't had that well a showing, even iG. All the teams in LGD's group weren't able to beat LGD 2-0, and Alliance aren't willing to take the chance of LGD getting too much momentum. The only team that beat them 2-0 was Dignitas, and they're in the lower bracket.
On the other hand, if they lose, Alliance drop into the lower bracket, and I think they feel that they can beat the lower bracket teams relatively easily.
What do you think?