I want him back here and especially wouldn't trade him. Make an example out of him. Treat him like a child... he's whining like one so let him go back home to Europe and make much less money in a lower quality league and continue to lower his chances of being traded / having any other NHL interest. If I were Holland, I'd tell him straight up "no matter what you say, I'm not trading you." Show him he has no leverage.
After being stuck in Europe for several month's he'll realize his agent fooled him and will fire him for a new one that is ready to negotiate with the Oilers for a proper return if he's capable of playing at that level. If he's doing better, either bring him back long term, or if he doesn't quite fit with the team, let him build up his stock and trade him. I just wouldn't trade him on his terms. Make him fire his agent and admit he's wrong before doing anything.
These young players don't have any appreciation for how they have such an amazing opportunity in front of them that not everyone has. They aren't all superstars that can control where they play or how much they make. They have to accept that it's a business. You want to be part of the NHL, you have to agree to the terms. You can't make your own as you go along.