I don't trust any US company, so it's not any more untrustworthy for me than DigiCert, for example. I'm dropping its name because they were offering free 3-year certificates and it was the best TLS experience I've ever had.
[0]: http://www.slate.com/blogs/future_tense/2015/12/14/kazakhsta...
It just coincidentally happens, that US controls 100% of root CAs and Kazakhstan (most likely) controls 0. So the later needs more audacious measures, while former can just issue a gag order to Symantec (or whoever is currently active in market).
CA system is inherently vulnerable to government intervention. There is no point in considering defense against state agents in HTTPS vulnerability model. It is busted by default.