alt Hacker NewsI think that's incorrect. Exclusivity would be something you grant to YC. These terms need to make sense to be valid. Claiming exclusive rights would mean they are forbidding YOU from licensing YOUR rights to anyone else.
Imagine Facebook claiming that by uploading images you are granting them exclusive usage rights to that image. It would mean you couldn't upload it to any other site with similar terms anymore.
Yes, this is what I mean in the above - the rights are non-exclusive so YC is also granted rights but not in a way that any of those other things listed after are true.