Your broom example is flawed and in no way a match to the situation. If you build a broom and I ask if I can see it and you say yes you can see it and you are

Your broom example is flawed and in no way a match to the situation. If you build a broom and I ask if I can see it and you say yes you can see it and you are free to make another one like it for yourself and make more to sell for everyone else, then you can't complain about them doing it. As for the "they didn't envision", then it's entirely their fault. If they put their code online using default copyright law, this wouldn't be allowed, they specifically picked a license that allow it.