[bbarthel]

Unless I am misreading the terms you are only submitting a URL to a REST webservice you create:

...Once you submit the URL of your service at the evaluation web site http://spellerchallenge.com/, a job will be scheduled to call your web service and post a status update to the Challenge’s community page...

Basically it sounds like you are giving them the right to use whatever service you create for the purpose of the contest. It would be hard for them to evaluate your entry if you didn't give them the right to do so. After reading through the rest of the terms, I can't find any requirement to give them access to anything other than that webservice and, if you win, a paper describing your research (no code requirement specified in any of the submission requirements and if you don't want their money, you don't even have to write a paper to participate).