The security level of a piece of code with good security is 95% coder competence and 5% language, i.e. language is irrelevant. One thing though is that language can add to the security problems if it has insecure tun-rime implementation errors.
One reason most security-critical software is written in C is that there, the coder gets full control. A good coder with skills in secure coding will do fine with C. A coder that does not understand software security will to badly in any language, but in C he/she might not even produce anything that works, which will be an advantage. Also in C, it will be far more obvious if somebody is clueless, which makes review easier.
But "language is important for code security" is even more wrong than "language is important for code reliability". Language is important for code performance though, but only in the sense that it can kill it. Good language choice can also make a good coder more productive (a bad coder has negative productivity, so it hardly matters...). This nonsense about the language being capable of fixing problems with the people using is comes from "management" types that are unable to handle people that are individuals. These utterly incompetent "managers" can be found in many large companies and they believe that in IT, individuals do not matter. Typically these "managers" are not engineers and have no clue what a good engineer can do but a bad one cannot. They also believe that engineering productivity can be measured in hours spent or that all coders are equal and just implement specifications, so outsourcing is a good idea.
