There is no way to guard against users installing malware themselves. No matter what kind of safeguards and check summing and signing you use for your application once a program has full access to a machine it can do anything, including bypass your safeties.
You can't fight user stupidity. In doing so developers do a disservice to their regular users. (The way Chorme prevents this issue is exactly an example of this because the app is no longer portable) No matter what kind of padding you add, stupid users will still manage to hurt themselves in the most unexpected and unimaginable ways.
I really despise this trend stared in the US and the rest of the western world where idiots sue companies for the effects of their own idiocy and this results in all kinds of redundant warnings on products that just serve to guard the manufacturer from stupid lawsuits. We should not strive so much to go against natural selection. Darwin awards exist for a reason.
http://inpursuitoflaziness.blogspot.in/2014/04/the-battle-ag...
Your casual casting of a swath of the population as "non-technical" notwithstanding, the point is still sound: why do you think that it's worth gutting this feature as a safeguard against someone being fooled into navigating to "about:config" but not worth removing sudo for the same reason?
If someone can be persuaded to abuse "about:config", why not sudo?
And as for locking down sudo, OS X is now "rootless" (System Integrity Protection) by default, preventing even sudo access from modifying some system settings.
This argument is becoming increasingly specious.
Firefox is the default browser on Ubuntu, where there is sudo. So do you acknowledge that it is consistent to keep this preference in at least the linux version of FF?