This seems wrong. It turned out that they specified GPL, and so the redistributor is violating the license. However, if they hadn't specified a license, then

This seems wrong. It turned out that they specified GPL, and so the redistributor is violating the license. However, if they hadn't specified a license, then the product would be unlicensed. Which would make the redistributor directly violating their copyright. If source code doesn't come with a license, that doesn't make it fair game. That makes it unusable by any third-parties.