Because, as is the case here, you are inviting person A to speak about topic B, because your audience thinks they may have something interesting to say about topic B, and not because they want to hear about person A's thoughts on topic C.

Ask the speakers to submit an abstract beforehand, during call for speakers phase. And pick those which you like. Not after the talk has been confirmed.

This editorializing is the equivalent of oppressive regimes inviting a famous band but asking them not to play their "controversial" songs, and the banning them with the obligatory surprised pikachu face when they do. It's not government censorship but it's the chilling effect of G & FB having too much control already.

(Or if the problem was that the organizer found those claims unsubstantiated, they should have cancelled the talk, or could have simply put up a big warning before and after the talk saying that this is the speaker's opinion, not necessarily 100% shared by the organizers ...)

The organizer's problem is not that it's not about the topic, but that the audience would become uncomfortable hearing, which is ridiculous.

Re-reading the organizer's email, I can seee their point. Politics could turn to be a blackhole topic that absorb all discussion energy, and then no one would leave the talk thinking about the "evil big tech" topic any more...

If I were the author's friend I'd tell him this, he threatened to derail his own presentation including the screenshots of political news.

The 1% of websites taking 98% of traffic should be alarming, but the focus-stealing headline there is "Income Inequality". If he had not put that as a headline and just made a throwaway oral comment (writing it down got him in trouble, and as I said, steals the focus!), it might've been more effective.

That's a good point: it is easy to derail with politics, I agree. Though living in a politically polarized country I just ignore political examples. Yeah, the guy is lefty, righty, religious, atheist, liberal, conservative. Ok, so what can I learn from him about the topic at hand? I don't have to become gay just because he's using Gay Pride backgrounds :)