Spinning Black Hole

At https://phys.org/news/2022-12-black-hole-spun.html … we have an interesting headline – without more data a black hole’s origins can be spun in any direction. However, in spite of that promising start, the story is quite a bit different. They are ot referring to the reality, or otherwise, of black holes, but to different types of binary black holes – merging black holes circling or spinning closer and closer etc. Later, we are told a new study by MIT physicians shows that when all binary black holes and their spins are worked into models of black hole formation, the conclusions can look very different – depending on the particular model used to interpret the data. A black hole can therefore ‘spin’ in different ways, depending on a model’s assumptions on how how the universe works. When you change the model, or make different assumptions, you get a different answer. Why are they surprised?