In my mind, this revokes and contradicts the previous clause: “We are free to use any ideas… for any purpose” is not at all limiting their usage.
In regards to the TOS mentioned in my original post, they are linked in the post, and are at…
Travis Holland

That is in the section “Communications other than Paper Submissions” (in the copy I viewed today).

Here’s what it says about “Papers. If You submit a paper or other content in connection with the Services, You hereby grant to Turnitin, its affiliates, vendors, service providers, and licensors a non-exclusive, royalty-free, perpetual, worldwide, irrevocable license to use such papers, as well as feedback and results, for the limited purposes of a) providing the Services, and b) for improving the quality of the Services generally.

This is pretty standard for cloud-based services like Dropbox, Google drive, etc.