That doesn't mean the interpretation is correct.
Free speech includes nude dancing?
No, despite the fact that someone's interpreted it to mean that. The meaning of free speech hasn't changed.
You're making a circular argument that amounts to the proposition that a court ruling, by definition, can't be wrong. If you're going to make that assumption, then there's nothing you can do to "prove" or "disprove" it. It's just an assumption.
The founders didn't know the true meaning
No, they knew what they were writing.
How do you know that? How can you make that statement? You have some direct line to God or to the Founding Fathers?
You give me some condescending line like "there is a true meaning to each of the parts of the Constitution" or "they knew what they were writing" and expect me to sit here and nod my head, going "Yeah, good point"?
You should know me better than that by now. How can you say that a USSC interpretation is "wrong"? Facts, inquest, facts. Not some esoteric 60's-type mumble jumble about "true meaning".