Publishers are under no obligation to publish anything they don't want to publish- and- as a matter of course- reject most of the work submitted to them. In the main they make their choices on commercial grounds. "Will this make us money?" is the important question- and if the answer is "no" the MS gets stuffed into the prepaid envelope its author has thoughtfully provided and sent back to where it came from.
I have been turned down by publishers. So have most wannabe writers. Was that censorship? There's a case to be made. The reason for rejection may have been been that our work was rubbishy, uncommercial, illiterate- but we had voices and the publishers had decided those voices weren't going to be heard and that's censorship, isn't it?
Technically, yes, but no-one was ever going to go to the barricades about it.
A few years ago anything Woody Allen wrote- however trite, pointless, self-serving etc- would have found a publisher, but times have changed and there are very good reasons why his work has become contentious. His publishers bought an Autobiography off him, then changed their minds and popped it back into the prepaid envelope. This is not something he is used to- but for the average writer it's a common experience. No-one has a God-given right to publication and it's not as if Allen has anything terribly important or startlingly fresh to say. We've been watching and reading him for half a century now. We know his schtick.
He has been accused of a horrible crime. He employs good lawyers and was found not guilty- but most of us thought the accusations plausible. How, then, do we express our distaste? We could turn up outside his Manhattan penthouse with pitchforks but that would get us into all sorts of trouble so what do we have left but the power- vested in the cultural gatekeepers- to refuse to finance his movies or publish his books? Sorry, Woody, but that's it; you've had a good run. Now, tootle off and enjoy your retirement.
It's not as if a rejection slip is the same thing as a gagging order. Authors with something vital to say have usually found ways to get the word out. You source a small, righteously-motivated press, you set one up yourself, you ask friends to circulate typescripts or handwritten copies. If the work is important enough it will make its way into the light.
And indeed it's never been easier and cheaper to self publish. If you want hard covers and gold tooling you pay a vanity publisher- and Allen is enormously rich. If you want to do things very cheaply you issue your work as an ebook.
Censorship is a big word for what has happened to Allen. It's more like an obstacle has been put in his way; a very small obstacle- one he could easily step over.