uBlock origin won't save you from exploits in Firefox. The only way it would've might save you is if you disabled first-party JS, which you might as well just disable in the browser itself.

Chromium still is the superior browser in terms of security and Firefox is way behind. Adding an extension so you _might_ have less security exploits in the foundation is a wrong tactic and should be avoided.

Real world threats generally aren't exploiting process memory errors or whatever. Unless they're in the shadier parts of the web, users are unlikely to encounter such things even when they might exist. Spyware and adware threats on the other hand are ubiquitous and highly likely to be encountered by nearly everyone. A web browser that doesn't mitigate that is simply not fit for purpose. It's a table stakes security requirement.