The government officials are "asking" private citizens to "ban" these books form their retail stores."
"they want New Jersey retailers to "ban the sale of [Coulter's] book throughout the state."
I respectfully disagree. Government officials can make life a living hell for businesses which upset them. Suggesting a boycott is one thing, but to suggest to businesses that they "ban" something is a chilling suggestion. You just had a cigar explode in your face.
I respectfully disagree.
Your slippery slope argument is false. Government officials have every right of free speech to advocate voluntary actions by private citizens. Governments don't have a right to harass private citizens.
Take your exploding cigar and stick it appropriately.