Okay, this is a fairly decent argument, but I think you need to read some de Tocqueville or Locke or Rousseau or Jefferson or...someone.

The problem with your argument is that you are ignoring the prerequisites that are necessary for a "free people" to be possible--prerequisites that the founding fathers did not ignore (though we can argue that they could have found better ways to meet the prerequisites).

Everyone understood quite well that a bunch of temperamental toddlers following their whims was not a sound basis for society or government. Locke stressed the importance of reason; Rousseau and Jefferson stressed the importance of education.

Let's be very clear about this. The Founding Fathers and the leaders of the concept of liberal Democracy all felt that citizens had a moral obligation to maintain certain traits of character, including sound judgment.

Locke (in On Reason): "He that believes, without having any Reason for believing, may be in love with his own Fancies; but neither seeks Truth as he ought, nor pays the Obedience due to his Maker, who would have him use those discerning Faculties he has given him, to keep him out of Mistake and Errour."

The United States is not founded on the idea that any random garbage that someone has collected in their head is as good as any other. It is founded on the idea that given opportunity to do so, people won't want to collect random garbage in their heads--that we should trust them to hold to intellectual virtue. That we have no means to effectively police it in no way is an argument that embracing intellectual vices is not an immoral thing to do. Unfortunately, social media has provided extraordinarily compelling proof that people love collecting random garbage in their heads under certain circumstances. So either we need to abandon democracy, or we need to push back against unexamined-belief-as-a-human-right. We can't stop people from gathering ill-founded beliefs, but we can judge it immoral.

This is different than endorsing any specific belief, unless that belief is so well-grounded that no-one of sound mind and at least minimal intellectual responsibility could have grounds to believe otherwise--and even then, it would take a strong argument to say that the belief should be hidden rather than exposed for the foolishness it is.

When you say, "But, in my society, claiming that beliefs that lead to speech can be “reckless” and therefore immoral (absent incitement to violence or crime) is a personal opinion.", this is not the considered wisdom of basically everyone who thought deeply about the classical liberal ideal.

Sloppy thinking unavoidably has real consequences, just like sloppy firearm handling does. Therefore, the moral responsibility cannot be avoided just 'cause that's how y'all do things in America. That we today live in a world of a complexity that Locke, Rousseau, and the others could scarcely have imagined just makes the moral obligation all the more acute.

So, no, you do not have an absolute moral right to your beliefs, no matter how ill-founded and unexamined. You have a right to the beliefs that you form as a responsible, mature, intellectually-virtuous member of society.

As a practical matter, there isn't very much to do about it other than try to educate our children well and socially hold each other to high standards. We have been falling far short on both.