I just investigated the issue you are experiencing, and it appears you are correct. The Rules Manager is not currently functioning correctly when you use the “DOES NOT CONTAIN VALUE” condition with the TPC Lookup widget. I will be creating an issue report, and this will be resolved in one of the next revisions of the product. I will make sure that this ticket is replied to with the revision number containing the fix.
Please let me know if there is anything else you need!