But we are talking about the GPL. If they used a different licence (as they eventually did after months of argument) it would not be relevant, but just the term

But we are talking about the GPL. If they used a different licence (as they eventually did after months of argument) it would not be relevant, but just the terms we got under GPL were not clearly sufficient, and their first response was "it's okay because we are fine with it". If it was an "it's okay because we are fine with it" in licence form, then it would not be GPL, but a different licence altogether.