I tend to agree, but I think my reasoning is more focused on pragmatism. In my eyes, this isn't so much about having a "clear and concise" scope (as you note in a commentin a comment).
The motivation of an SE site is to provide useful information to askers and readers. Expert participants on Law and Open Source are likely to have more knowledge and experience in licensing; it is more closely tied to their specialties. This isn't like the difference between Movies.SE and SciFi.SE, where overlap between the two subject matters is so broad that experts at each site are roughly equally capable of answering questions that could be on topic for either. The target experts of Law and Open Source by definition gives them an edge. As a result, an asker is likely to get a more complete, more thorough, and therefore more useful, answer on those sites than one where the experts primarily specialize in software development.
I do have one concern, though: are there questions about software licensing that would be on topic here currently but would not be on topic at the other sites? If banning these questions from SoftwareEngineering.SE could result in useful questions losing a home on the SE network, I would rather err on the side of caution. What does a look at the existing questions about the topic tell us in this regard?