I reckon you could charge a certain % of the pledge to prevent this kind of trolling. You'd still be allowed to back out, but the money would stay on Kickstarte

I reckon you could charge a certain % of the pledge to prevent this kind of trolling. You'd still be allowed to back out, but the money would stay on Kickstarter and cannot be withdrawn, but instead just put towards another campaign (but that money no longer counts towards the reserve of future campaigns). This makes sure that the troller gets their money locked up in Kickstarter. Few if any legitimate Kickstarter funders would be bothered by this and if they really were bothered by it, Kickstarter staff could evaluate those few incidents on a case by case basis.