Salas' time in Juve failed, much because injuries and Lippi. So yes i dont want him back to Juve to see him fail a second time. It is smarter to use him in a deal to exchange with some player from River, maybe Cavenaghi since Juve has been interessting in him.
At least Cave has more potential to success, since he is younger too. But im not so very interessting im him.