WHAT PART OF “MAKE NO LAW ABRIDGING” DON’T THEY UNDERSTAND?

I don’t remember who it was, but a commentator who writes about First Amendment cases, noting the frequency with which government agencies (whether well-intentioned or not) attempt to restrict free speech, said something like: what part of “make no law … abridging the freedom of speech” don’t they (those attempting to restrict free speech) understand?  
I have said it before: the government cannot restrict speech based on its content.  That means if a t-shirt maker doesn’t want to make a t-shirt with your slogan on it, the government can’t force him to, or penalize him if he refuses, no matter what your slogan is.
It’s the Nazi parade scenario in reverse: no matter how beneficial you think your message is, the government can’t force the t-shirt maker to say it, and no matter how detrimental you think someone else’s message is, the government can’t force the t-shirt maker to not say it.