Taking away the megaphone is simply not incompatible with free speech and there will never exist a single person or institution who will adhere to what you say free speech means.
Depends on the circumstances, it very well can be. Who are you to decide who gets a megaphone or not? But abstractly you cannot really confirm or deny such statements.
But that is besides the point. The criticism of free speech isn't new, the arguments are always the same and usually those that argue for more restriction do end up being wrong. I don't see the path developing differently here.
To ask why Trump can capitalize on these issues, a careful reading might be appropriate as the result wouldn't be too surprising without needing to much predictive capacities.
https://en.wikipedia.org/wiki/Freedom_of_speech
Your interpretation is widely spread but also wrong. The government is only a relevant party if we talk about specific laws.
> As a moderator, I also ban people who are just obnoxious and loud without any substance.
You then don't follow the principle of freedom of speech, simple as that. That is no crime, but you aren't liberal in these cases either.