Freedom of Speech refers to the State (governments in general) not being allowed to censor, etc.
"Freedom of Speech" does not apply to private property. For example, if you start talking loudly about anything at all in a movie theater, you will told to keep quiet or leave. If you persist, you'll be escorted out. Because those are the rules for entering a movie theater.
These are Nexon's forums, and as such, Nexon has the right to restrict what may or may not be discussed here, and how. They have set out these rules in the forum Code of Conduct, which you are encouraged to read.
Specifically, you, and others in your thread, made baseless accusations towards whoever plays Kanna or disagrees with removing Kishin, claiming they are all hackers or botters. That is against the forum rules and led to the thread being locked.
If Nexon wanted new characters to have potential badges, they could simply re-run the Sengoku High event. All the code for it is already in the game, all they need to do is set a start and end date and everything will run as it did many times before. It's clearly not "programming effort" that is the problem.
Transferring characters into Reboot will never be allowed.
One of the basic principles of Reboot is that each character has to progress by itself, there is no trading. Characters in other worlds have gear and other items they purchased from other people.
Another basic principle of Reboot is no advantage through paying cash. Characters in other worlds have equipment that was enhanced using cash cubes and scrolls.
So, allowing characters from other worlds into Reboot would be completely unfair to people who play in Reboot by its rules.