Travis Kalanick has never blackmailed journalists. Emil Michael, an Uber executive, brought up the idea as an ethical hypothetical.

http://www.huffingtonpost.com/nicole-campbell/what-was-said-...

Specifically, he asked Ben Smith of Buzzfeed whether it would be ethical for Uber to hire someone to investigate and report to the public true facts about a journalist (as opposed to journalists investigating and reporting true facts about people involved with Uber). Ben Smith evaded the question, most likely because he didn't want to admit that as a journalist he feels that's a privilege which should only be afforded to members of his club.

You are right that Lyft doesn't do much politics. Instead, Uber spends money fixing political problems and Lyft then freeloads on them, making money in the better world that Uber created. For me, that's a strong reason to prefer Uber to Lyft.