I started using Signal because I don't want people seeing the messages I post. But in the end it's only trust that makes me think Signal is safe to use.
A lot of people also trusted Juniper. But that trust is gone. And not only for Juniper. What about other brands? We don't know.
One has to assume that all are back-doored. Mobile phones are inherently not trustable.
Same goes for all major firewall vendors. If you going to hack one of them as a nation state, then you're going to do all of them.
While that used to be true, based upon recent history we, unfortunately, can't blindly trust HTTPS to always be "secure" 100% of the time anymore -- whether due to things like Heartbleed, fake certs signed by a root CA, protocol attacks, or some other vulnerability that hasn't even been discovered yet.
Trust is something delicate which works best by using face to face communication.
So it's ok not to trust everything you read.
But this story is about private communication not being as private as thought.