As this thread has died, I'll leave off with a couple of parting comments--as I previously mentioned, the idea of 'reasonable' will change depending on who you ask. When you say 'We should figure out...,' rather than leave reasonableness to an individual 'I,' now it's given to a multitudinous 'we.' That is, the idea is given a democratic flavor, wherein if a majority (even by just one person) thinks this or that speech act is unreasonable, it can enforce its prohibition.

Given your reasonable fear of manipulation/propaganda by those in power, can you see where this might go wrong?

Thus, as Americans, we've done more or less what you've asked--we laid out the ideal, 'Congress shall make no law...,' then we set our local, state and federal bodies of government on the problem of how to work within this ideal. Which, if the solutions are reasonable, will remain law. Which, if an individual (e.g. a flag burner) or a multitude (e.g. a religious sect) thinks are unreasonable, will be challenged through later legislation or through the courts. Potentially landing at the doorstop of a nine-member group called SCOTUS who, using their collective wisdom, will tell us whether we've (or our bodies of government have) gone too far. (And if we as a nation disagree with their decisions, we as a nation have remedies for that as well.) All in a world of moral-less actors.

Is this not reasonable?