This could be what he's referring to https://blog.mozilla.org/blog/2013/01/28/privacy-day-2013/

It could also just be overall common sense: a nonprofit vs a company built on data. Who would you expect to care more about keeping your data yours?

Chrome comes bundled with Flash and a proprietary PDF renderer; proprietary plugins, especially Flash, have historically been a rich source of privacy and security problems.

The fully open-source build of Chrome (called Chromium) avoids that problem but is more difficult to install on some platforms.

In theory, Chrome sends your entire browsing history over to Google, since its unified omnibar doesn't distinguish between searching and typing in location. Firefox (and any browser that separates the location and search bar) doesn't have this problem.

To be frank I'm not sure how Google uses this information, but it does make me laugh when the whole Ubuntu Dash searches Amazon thing blew up. It's the same thing, really, yet nobody talks about Chrome at all.

there is conceptionally no support for functionality akin to noscript (as in the firefox addon, not the chromium plugin with less functionality), request policy, etc. even adblock works better in firefox.

allowing these plugins is a decision that also has drawbacks. the browser will need to support synchronous callbacks (i.e. to possibly block http requests). these can block the browser, something chromium plugins cannot do (at least so easily).