JP, in the example you stated, you are correct. However, take your milk crate and place it in the middle of a restaurant, or a store, or a movie theater, or a college classroom, and your right to freedom of speech no longer applies. You may be asked to leave, and if you refused, you could be arrested for disturbing the peace or for being a nuisance and disrupting the orderly conduct of business.

The same applies to the workplace or to investor message boards being operated as a business. You agree to the conditions and restrictions set by your employer, which limits your freedom of speech. In signing up for a message board that operates as a business, you also agree to their terms of service. If you believe you have the right to post anything you desire, you are wrong. Your right to free speech doesn't extend here if you violate the terms of service you agreed to by joining.

I believe the problem here isn't that the board limits free speech, but when someone repeats the same message a hundred times trying to gain support of others, when clearly others don't see it as a concern, then it might be appropriate to start to censor the "concerned" shareholder, because clearly they can't accept that others don't share their concerns and they start to become a nuisance and disrupt the orderly discussions of other shareholders.

And for the record, I'm pursuing a computer science degree in order to change careers from nuclear power to software engineering. The Ethics of the IT Professional course is a required course, and has really opened my eyes to the intricacies of a number of subjects, including freedom of speech, particularly in regard to the Internet. Prior to the course, I was under the same misconceptions about freedom of speech that most people believe.