Siphoning implies they are doing something untoward with it, which does not appear to be the case here. They're already building something that will let them do a mass refund; they have decided to use that tool to send out this money, at some cost to themselves. What could be wrong with that?

exactly. I know the founder. He originally had no plans of creating an alternative to kickstarter. He wanted to create great hardware products and use Kickstarter to fund the development. After running into Apple approval issues for POP, realizing how a less than honest company could ship a shitty product and keep the $140k that backers had provided, he realized just how bad kickstarter is for funding & creating hardware products. Not only is he giving the money back - this inspired him to create a better alternative for creating and backing products. It is a classic founding story.