I just gave you an example where it turned out not to be safer: Heartbleed. Malicious bugs can be well hidden, also in open source code. The openness shouldn't give you a false sense of security, because it doesn't imply the code has been audited any better than some closed source code.
I disagree that heartbleed is an example of not being safer. If everyone's SSL was a closed-source library, then we would be considerably less safe.
But to carry the analogy to a closed-source web site that you just connect to, as is the topic of this comment thread, we'd certainly be less safe if we routed all SSL traffic through an unknown system on the web that had the opportunity to decrypt and encrypt.
