What the fuck.
The downside of pushing them to that is that that browser will be unlikely to get regular security updates and will likely hide the interception.
But I disagree with the response that says we should do nothing. In fact, corporate root certs should be blocked / ignored by the browser in the exact same way and for the exact same reason. The only exception should be certs issued for a limited number of domains that are only active in a specific developer mode that can be enabled by knowledgeable users.
Sure, technological solutions can't solve this issue 100%. (My employer can also fork a browser.) But acting as if everything is OK when the connection is being MITMed is wrong and browsers shouldn't do it.
Technological solutions can't solve this at all if the entire stack is controlled by the interested party.
In the case of government snooping, you (theoretically) own the end device being used for access. In the case of corporate snooping, you're using corporate owned and managed devices. There is absolutely no technological solution that exists that will prevent another person from building software for (or selling to) corporations who need to snoop on their employees. Considering the selling price of appliances that perform these services (e.g. Bluecoat's range), the cost of a browser is negligible in comparison.
I don't think it's fair to conflate a lack of privacy on corporate owned devices with a lack of privacy on your own personal devices.
Stop thinking about the country with literally less than 1% of world internet users and start thinking of the reputational damage a less than charitable presentation of your collaboration with a totalitarian state against your users would do to the other 99%+ of your market.
Malware forks of open source projects (and closed-source software!) are not a new problem.
In reality, being one BGP trick away from a mere dedicated individual or corporate owning certs for your domain is an actual risk today.
In fact, you're making it worse because you're giving legitimacy to a government that is conducting actions which we shouldn't consider acceptable. If the US government started doing the same thing, I would really hope that browsers would block those certificates too.