This isn't caused by C though, it's due to an error in Ragel source code that is then compiled to C. It would be like saying x86 is a flawed design because someone can write strlen((char*)main) and compile it.
It's also not a flaw in the Ragel state machine compiler, and even if it was, the Ragel compiler is written in sepples, not C. C code only became involved at the very last stage, when the Ragel compiler is actually generating output.
The error existed in the Ragel source file, and was propagated into whatever internal representation the Ragel compiler uses, before any C was even involved. This really isn't the sort of thing you can reasonably blame on C, the C compiler only did exactly what it was told to do. That a compiler gives invalid output when given invalid input is not a meaningful criticism of the language.