The point is that the climate of free expression that you wish to defend has never, and can never exist. The nature of society is to have social standards.
Every community gets to decide what is acceptable within that community.
The biggest difference these days is that today’s college students have chosen the inclusion and safety of marginalized groups over the current majorities preference for mocking those groups.
The better example in America is racists. We used to elect them into office, pay them to speak, and invite them to univeristies to give talks about the dangers of integration. Over time, we decided that behavior and those opinions are abhorrent. They were disinvited, and now are not welcome at all in most social circles I run in.
That’s not the case universally, but I certainly hope it is in my lifetime.
The vanguard might be fallible, but so is the main guard. There’s a reason we make fun of our racist grandparents and less racist parents. The younger generation is over the marginalization of people based on who they are. We are more than happy to marginalize people because of what they think because they can change what they think.
Furthermore, the marginalization of ideas while a real danger, seems much less threatening given the disgusting ideas aired over the internet on a daily basis.
We protect the openness of that system with extraordinary vigilance. Even if many would like to see terrible ideas go extinct, we would rather see that happen in the marketplace, where communities and individuals choose which ideas they would like to include and which to exclude.