What does it mean to have a right that you can be effectively prevented from exercising? What is the difference between a right that one is not allowed to exercise and a right one doesn't have?
He will not be barred by the government from doing all of those things. He is not being prevented from exercising his right to be a CEO. He was asked to step down by many people, as is their right, and he did.
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.