Only bringing this up from a few pages back, since I haven't seen anyone giving the correct answer (I might have missed though, since I skipped over long parts, and will probably tune out of this thread soon):
- Freedom of speech means that the government cannot prosecute you for what you're saying, that the police cannot arrest you for your opinion. (with exceptions, like inciting violence, screaming fire in a random situation, hate speech, libel, etc; the list is actually quite extensive, if you want to interpret stuff in the most broad way)
- It does not mean that anyone is obligated to make other voices heard though (e.g. the media doesn't have to report about it)
- The other concept related is censorship. This again states that the government cannot blacklist any topics, all can be talked about
- It does not mean that anyone is obligated to give coverage to any topic or to listen to them
- Basically you can do anything, as long as someone supports you. In the worst case, you can always print flyers at home, and distribute them, because you don't need support for that. You can have your own website/blog whatever, if you find a host for it. You can express your opinion. It might not be heard though, and in how far there is pressure to not make it heard within legal boundaries, that might tell something about... not sure.
- In how far a generally hostile environment is not conductive to freedom of speech, that is a different problem, partially also related to the "Chilling Effect", which basically means that the environment puts pressure on people to not exercise their rights.
tl;dr: Private companies not supporting someone in expressing their opinion does not conflict with the concept of freedom of speech.