The concept of free speech, at least in our country, relates to governmental infringement of the right to free expression. When person A says something person B disagrees with, and person B says "you can't say that, that's racist", nobody has lost the right to free speech. Both parties have expressed themselves freely with no governmental intervention. Maybe person A feels their words have been shot down, but they are still free to say the exact same thing again. They might get censored by a private organization, but that's well within the rights of the private organization.