[The_Long_Run]

Siavash is cunning (nothing wrong with that of course) he has not said he's going to give it to charity, he has tried to get his HMs to form a pact to give it to charity. He knew they wouldn't form that pact so he was safe to suggest it. In the hugely unlikely event that he comes out the winner he just says, "no we didn't form the pact but I'll make a donation" (it will be pretty small, like Rachel's £10,000).