Most constitutions (the one in the US for
guarantees every citizens right to free speech. Most countries also
have laws that makes saying and publishing certain things illegal. In
most countries with "free speech," you are allowed to put "almost any
poster you want on your front door." Similarly, Wikipedia allows you
to put almost any description of yourself you want on your user page.
Quite the contrary, it is important to emphasize that there is no
protection for offensiveness for anyone.
This kind of liberty is important for governments to grant because
(A) They have a monopoly on coercion and
(B) They do not grant you a right to fork, and they do not always grant you
a right to leave.
Neither of which applies to Wikipedia.
"If you don't like it, leave" doesn't apply to federal governments, and
can really hurt you. The analogy between Wikipedia and a government, or the
US Bill of Rights
is completely out of place.