It’s not saying to be a jerk to people.

“Masking” is when a person with autism hides associated mannerisms in order to blend in with neurotypical people (make themselves “more palatable”), such as avoiding hand stims or atypical (but still healthy) reactions of enthusiasm.

“Unmasking” doesn’t mean giving up anything you do to be considerate of others (such as not giving unsolicited 15 minute rants about my hyper fixations); it just means not trying to pretend to be a neurotypical person, consciously or subconsciously, and to just be your authentic self, autistic self.