This may be an unpopular opinion here but if the TorBrowser folks cared about security they should switch to a Chromium based browser. The sandbox provided by it would be robust and well tested as it's used in Chrome.
I don't see why the two objectives of having a secure browser and the privacy/anonymity provided by Tor have to be diametrically opposed. You can have both.
Because removing all of the Google-related features from Chromium would be a very large task indeed. Quite a few people have discussed it within Tor (and IIRC some people started working on it) but it might not be as good of an idea as you might initially think.
There is currently only one maintainer of that code, and there is this disclaimer in the readme:
> DISCLAIMER: Although it is the top priority to eliminate bugs and privacy-invading code, there will be those that slip by due to the fast-paced growth and evolution of the Chromium project.
I don't see why the two objectives of having a secure browser and the privacy/anonymity provided by Tor have to be diametrically opposed. You can have both.