It's a commercial product that also happens to be available under a free license you can't use. How does the second part impact the first?
Edit: it seems the implicit context in your post is that you would use this if it were free under a permissive license, but not if it costs money or is GPL. That's not an uncommon position, but it's not something that rises to a multi-paragraph complaint on HN. You're complaining about the "GPL" instead of complaining that "the authors want to charge money", and that seems inequitable and unfair. If they were just another tool vendor, you wouldn't have posted: basically you're punishing them for releasing free software.