A person can commit fraud over the phone, with multiple victims. The phone company is a facilitator of that fraudulent act. Yet the phone company is always immune from prosecution for fraud. I think IGG will always stay out of the loop. Once they intervene, if only one time, then they are open to multiple lawsuits. Actually, in my opinion, and I am not a lawyer, I think kickstarter is more liable for campaigns on its site, than IGG is right now.
I think that is a possible defence, but very weak. If IGG accept any project without looking at it, they might argue common carrier, although that tends to apply to communications. Websites have no real legal definition, they are a virtual place. What laws apply depends on what transactions the website facilitates.
Are they publishers? Yes, the law has determined they are liable for libel, and copyright violations by users or contributors.
Are they shops? Yes, they are subject to consumer sales laws if selling online.
Are they banks? Yes, if they do financial transactions, they must follow financial laws and be regulated.
So I think that the precedent is set such that crowdfunders would find it very difficult to claim anything like common carrier.