I don't think either is disloyal it's just a young player taking control of his destiny that is all. Pogba didn't see signs he would play so chose to leave same with Thiago.
Well, every young player who leaves a club when he is a product of academy (although the coach says that he'll play in the future) is a bit disloyal.
No worries about me for that though, I was just replying to someone calling Pogba cnut for leaving us, but Thiago is a good guy for coming to us. The only way this makes sense, is he's a cnut but our cnut.