It is against the policy, so there is some risk. Registering is probably not that bad, since you would likely only lose the name and reg fee in a nexus dispute. If someone had a UDRP claim, they would probably just file a nexus dispute instead since it would be a slam-dunk case.
The risk comes in developing the domain, Once you've put effort and money in development, you could lose it all without nexus, and give up everything you've worked for.