Are you opposed to all forms of coercion?
Anyway, I'll concede that force is probably the wrong way to go about it... the government could provide incentives for exposing people to diverse viewpoints, but forcing people to do so is a bit extreme.
Anyway, that's a different discussion altogether. While I think force may be necessary in some aspects of society, I concede that applying force to the realm of discourse is probably a bad idea.
When someone, such as a rapist or a politician, has proven that they're incapable of peaceful behavior in society, we have the right to defend ourselves from them.
IOW, self-defense isn't coercion. The coercion has already been committed by the criminal. If you're walking down the street and I mug you, I'm applying the force. You, in self-defense, aren't being "violent" in your intent to protect yourself. You're trying to stop the violence I'm committing against you.
I guess what I'm saying is I wish people would worry less about labels and more about principles.
To get back on topic a little, the government using the tactics as laid out by Sunstein is a fraud being perpetrated by the force of government so it rings all kinds of bells.