I think you are identifying a weird gray zone because there is a currently a dispute underway between Bob and Virgil, which is centered around the IP and trademark aspects of the Bearhawk airplanes. It's weird and gray for all of us.
Something to consider is that Bob has always sold a set of plans as a license to build one example of the plane that he designed. There's a dual purpose there, conveying information, and conveying license to build. Bob's plans are copies of the hand-drawn originals, and each set has a unique serial number. It has always been possible to build a Bearhawk without a genuine/licensed plan set. I personally wouldn't do that because I don't think it is ethical.
I hope that the dispute becomes resolved soon, and we can eliminate this gray area. But seldom does litigation move fast. Until it is resolved, if you have concerns about this aspect of plans ownership as it relates to building a plane and calling it a Bearhawk, I would encourage you to reach out to Virgil and to Bob, and decide what you are most comfortable with from the ethical perspective.