According to fahrenheit 451, what is the meaning of freedom of choice?
I'm not completely sure this is what you're after, but if you apply the idea of freedom of choice to the novel, Fahrenheit 451, the central issue is probably that a person should be able to read opposing arguments (through books) and make decisions about ideas and issues for himself or herself.
Beatty, for instance, cites the fact that books don't agree as one of the reasons books shouldn't be read. The idea is that ideas should be kept simple, that people should simply do what they're told; that life should be simplistic. Reading books makes one think, and reading opposing viewpoints makes one have to decide. The novel suggests that people should have this choice, however. Peace of mind at the cost of the ability to think is numbing, not peaceful.
To me, the society in the book does not believe in any sort of freedom OF choice. I think that it believes instead in freedom FROM choice.
For example, Captain Beatty tells Guy Montag that in their society you do not have people born free and equal. Instead, you have people made equal. This, to him, is freedom. It is freedom from having to compare yourself to other people.
I suppose you could say that the book is arguing that this view is wrong. It is saying that people should be free to think their own thoughts.