As currently described at your link, that one doesn't seem so hard. Person 2 simply says to Person 1 ‘If you don't read it, then I will.’, to which Person 1 will agree. There's no real force involved; if Person 1 puts down the book, then Person 2 picks it up, that's all. I know that this doesn't change the fact that the theorem holds, but the theorem doesn't seem terribly relevant to real life.

But Person 1 is still being manipulated by a threat, so let's apply the idea of freedom instead. Then the preferences of Persons 1 and 2 may begin as in the problem statement, but Person 1 (upon sober reflection) allows Person 2's preferences to override Person 1's preferences, when those preferences are only about Person 2's life, and vice versa. Then Person 1 and Person 2 both end up wanting y,z,x; Person 1 grudgingly, but with respect for Person 2's rights, gives up the book, while Person 2 refrains from any manipulative threats, out of respect for Person 1.