Agree with much of what Blocky is saying on Ryder though like most others here I don't ultimately believe Ryder has much/any future playing for NZ.
Jesse will never come out and say "I love playing for my country, I want to be in the NZ side for the next five years" because of fear, more than anything else. That's what I truly believe. You won't see him do the big Kevin Pietersen like gesture because ultimately he has a massive fear of abandonment and expects that the worst will happen. He also would be risking the whole "I'm too cool for that ****" ethos that he's built with his friends.
Agree with the obvious diagnosis that like a lot of people with a lot of superficial confidence and bluster, Ryder is insecure and fearful underneath. But I think there's another angle to that. He's scored runs at international level but he's never really scored runs against the people I (and he) would think of as The Big Boys. At some point in his early stint in international cricket I think the realisation snuck in that, unlike ever before, there were bigger fish in the sea than him. Bowlers that he couldn't just deal to, particularly those that were genuinely quick and intimidating, and that he couldn't see any way of dealing with in the future either. Fear of failure and humiliation snuck in. Other batsmen doubtless face the same feelings but may have more mental/emotional reserves to call upon in order to face that challenge, however for Ryder I think once that thought was in his head then he went with the well established (in NZ) fallback option that you've pointed out -"too cool, not gonna try". I expect that if he was facing Steyn and Philander or Johnson tomorrow we'd just get wild swings and slashes every ball because he doesn't genuinely believe he can play them.
That's why managing him and letting him manage himself comes down to patience, respect and not imposing stupid restrictions. That doesn't mean you let him run around at night every night getting ****-faced and being hammered while playing, but it does mean that if you want to eradicate that behaviour, you have to accept why that behaviour occurs in the first place.
Tend to agree with this too though what it runs up against is the culture most teams and their coaches/captains try to build. That culture of team-first, individual second repeated again and again and drummed into everyone. Anyone that steps out of line and shows non-team-first behaviour and does not comply is strictly put in their place. There are other examples of that - I see Jeets backing away against Steyn in South Africa as an example - it would have been seen as an affront to the team-first culture and his dropping was more a punishment for that violation than for any direct cricket reasons. The fact that there was nothing to gain whatsoever by him standing there and wearing a ball from Steyn was besides the point… in fact it only increased his opportunity to demonstrate his team-first approach. A few arbitrary rules and rituals always seem to sneak in to that culture too and perhaps these do strengthen the team bond as well. Most of this culture is seen as positive and it does involve a lot of internal reinforcement; a lot of players like it.
But then someone like Ryder comes along and needs exceptions made for him, because he will most definitely exhibit some non-team-first behaviour. People will say his behaviour is not acceptable and it will be seen as undermining the team culture and also the authority of the captain/coach. Authoritarian elements within the environment will try to pull him into line. Unless they’re smart/careful the captain and coach will likely back themselves into a corner by escalating things; warning the offending player, last warning, ultimatums as Blocky talked about. They end up in a situation where they either kick the offending player out or completely lose face themselves.
There are ways to do things better than the above but they do require a compromise on that culture, and in Ryder's case much of this is already established history anyway.
But in terms of his actual attitude? His move to Otago was all about getting away from bad influences and rebuilding. His time in Essex was all about keeping some consistent cricket going and not having a massive layoff/downtime like he has had in recent seasons. I think the moment you slap an NZ badge on his chest and say "We want you to set up test matches with your batting" is the moment he'll start to show he can.
Playing for Essex is fundamentally different to playing for NZ and for the people he has a long and difficult history with. He has an established relationship with NZC, coach, captain, some players etc that is to a greater or lesser extent antagonistic. Particularly as Ryder will see some of them as just more of those types that have tried to cast their authority over him, who’ve abandoned him and disrespected him. Does he really want to succeed at cricket with and for those people? In all likelihood I think not.