There are 2 different things - JP Morgan's position and Jamie Dimon's views. They may not believe in Bitcoin, but they will still buy it for you for a small fee. You cannot expect JP Morgan to ignore an opportunity to make money, just because it's boss believes that it is a bubble. Even if it is a bubble, only the investors get hurt.
Exactly! Jamie was negative because this was his personal stance. He didn't like it, he didn't see value in it and he liked to go public with his statements because it put him in the spotlight. After it became known that not only his daughter but employees are into Bitcoin he quickly backtracked and is now slowly becoming a supporter. He won't make up his mind though. If Bitcoin starts to crash he'll be among the first to say "I told you so".