That's an incredibly bold statement given that there's almost no-one writing Bitcoin applications in C / C++ with the exception of Bitcoin Core itself. Equally the demographics of people writing the tiny amount of C / C++ code out there is very different than the demographics writing in more modern languages.

Fact is right now we just can't say anything about what approach is better based solely on where the most bugs have been found; we can say other industries have consistently been moving away from C and to a lesser extent C++ due to the difficulty of writing secure code in those languages.

You're also conflating two separate problems. It may turn out that writing consensus-critical code in other languages is harder, but that's a very different problem than writing secure code in the more general sense. Equally it may turn out that better approaches to writing consensus-critical code are more important than what language you choose to write it in. But right now we just don't know.