In the real world they would be too busy fighting lawsuits to think of buy backs under those rare circumstances - but the stock market does not follow all the rules of the real world.

Stock buy backs are common but usually represent a fairly small minority of shares, are publicized and have the implied or express consent of stock holders because such usually benefits stock holders.

I've never witnessed the situation you describe. With no published bid nor ask and if even accredited investors are not allowed to trade no info co's and if brokerages take a stand like etrade -meaning they will not even allow trading in such companies -who would the company be buying shares from? No Broker would be allowed to publish quotes so all buying -if even possible - would be blind buying.

Once the free for all games begin the shares usually end up being confiscated (sorry -frozen-same difference) by the dtcc (lots of long articles re them) which owns the underlying stock certificates of all usa stocks.