I have been part of the left for decades, and never once in all that time have I EVER been asked to support the banning of a single book.
I have however gotten almost weekly request to help STOP an attempted book ban by the right.

I am pretty sure in fact that I know the left far better than you do, since your entire understanding of it appears to consist of strawmen so outrageous it's a wonder you can  believe your own words. 
You think Ebenezer Scrooge and the Ferengi are unfair depictions of capitalism - they are about a billion times more accurate of it's reality than your views are of progressives.

But either way - you specifically described the author's (misguided) suggestion as being bookbanning. Because, apparently, you think parents making rules for their actual children is somehow akin to dictatorships in oppressive governments. 
I won't be taking any parenting advice from you - and like most lefties, I am usually criticized by the right for not having ENOUGH rules !