If I interrupt the CEOs speech at a public conference, yeah, I fully expect to get canned. It’s not like this was an internal all-hands or summat.

Oh, it was an event with custoners invited? Yeah, that's grounds for dismissal anywhere, I'd think. Even in countries with strong labor laws you could just show the court the video recording of an employee doing willfull sabotage.

If I did what the protestor did at an internal all-hands or summit I would expect to get canned as well. You can't go up yelling and interrupting the CEO. In an internal all-hands/summit situation you need to maintain decorum, if you have a point you wait until a QA session, then express your displeasure.