You're misrepresenting the report in order to justify your bias. Direct quote from the report:
This is not to say that C is less secure than the other languages. The high number of open source vulnerabilities in C can be explained by several factors. For starters, C has been in use for longer than any of the other languages we researched and has the highest volume of written code. It is also one of the languages behind major infrastructure like Open SSL and the Linux kernel. This winning combination of volume and centrality explains the high number of known open source vulnerabilities in C.`
In other words the report explains this with 1) there being more C code in volume and 2) more C code in security-relevant projects (which are reviewed more by security researchers). It also states
explicitly that your conclusion is not to be drawn from this.
