an inalienable concept as free speech
Free speech is not an “inalienable” concept. To be honest, the adjective “inalienable” doesn’t well describe a “concept”, more “right” or a “privilege”. Nobody can take away a concept from you, only the exercise or realisation of that concept.
That said, the Lemmy dev’s code of conduct is not a binding document, and given their political views, I wouldn’t even bother opening it if I was adminning my own instance. And nobody owes you your freedom of speech - if an instance decides to enforce the rule “no talking about politics on Wednesdays”, nobody has any right to anything else. Preference, sure, but right? No.
Surely just pirate it so you can read it on your timetable, and take the book from the library when it’s your turn to give that author the lending stats?