It's all guessing and it's all speculation - nobody knows why Juve sold Kean. That's precisely the point.
Right, but if one were to make educated guesses, the list would look something like this
1. He only had a year left on his contract, and Juve had to sell
2. He is 19, with not a huge amount of game time under his belt. The demand may not have been there
3. He didn't want to stay at Juve for any longer than he had to, having been racially abused and see his captain back his abusers
4. His agent has a known relationship with Marcel Brands, our director of football
5. Most likely, a combination of all of the above
Souness went straight for the "Adebayor" button because he is a dinosaur with no other point of reference or info apart from another black player he vaguely remembers from a decade ago