He's still allowed to be CEO of Mozilla. (Calling a specific job posting a "right" seems a stretch — do I have the right to be CEO of Mozilla? Where are the complaints that I'm being effectively prevented from exercising that right?)

Nothing and nobody forced him to resign. He could've weathered the storm and risked Mozilla's most valuable asset, its goodwill, over his beliefs. It would've been a terrible thing to do to the company and made him a terrible CEO, but nothing stood in his way.

Claiming that someone's rights were violated because he voluntarily quit his job is patently absurd.