They built it using some publicly available resources. These resources are available conditionally, subject to licenses (such ad GPL). Which is fine.

The problem is that their product sometimes produces verbatim copies of licensed works, without attaching licensing information. This not only goes against the licenses under which the original authors made these works available. It can also put the product's users in danger of anything from bad publicity to a copyright lawsuit.

CoPilot is a very interesting research project. It's not yet an acceptably mature product though.