Mozilla will certainly continue to sign my piracy-enabling add-on that is perfectly legal in many jurisdictions worldwide, even after an US court ordered them not to sign it explicitly?
I also heard mozilla got an NSL for my "Ed Snowden for president, Find out more on wikileaks" add-on, or rather, I didn't because NSL.
Then again, I hear a brought coalition of human rights, LGBT and feminist groups lobbying mozilla not to sign my "Find nearest public stoning near you - Saudi Arabia Editon" add-on any more, effectively blacklisting it worldwide. But mozilla will keep to their promise not to blacklist my stuff and my regular users can still use my add-on, right? The creator of Javascript and mozilla CEO Brendan Eich will make sure of it... Oh wait...
Speaking of which, what about my "mozilla - not protecting Brendan from harm was shit" add-on, is that compliant with the mozilla trademark policy that I need to abide by per https://developer.mozilla.org/en-US/Add-ons/Add-on_guideline... ?
Yes, those examples are a bit contrived, but actually not that much over the top. Also, please note that I do not necessarily condone these things ;)
My point being: Security through tech-enforce policy is nice and has a lot of upsides as you say, I agree, but it also may have downsides you aren't even aware of.