What harm can possibly a person from Iran do to this project, or US, or us citizens or other people from the world, by contributing to this project or other one

What harm can possibly a person from Iran do to this project, or US, or us citizens or other people from the world, by contributing to this project or other ones on TopCoder?! Ok I understand that you can not sell things to us, because you think that we may misuse them for terrorism (Although real terrorists - not the people - can find what they want easily) but seriously what does contributing to an International project can do anything with politics?