Nobody is denying Kickstarters rights and I would be the first to defend them if anybody ended up suing them over this, but actions have consequences, even for companies. If they don't cave in to the next offensive project (t-shirt with "I have a gun because I have a small dick") then they will stop being percieved as neutral and will hurt their business with some groups. As a company, they are trying to make as much money as they can, so they should consider the consequences of turning away people, even if they unquestionately have the right to do so.