The C++ language is close to a superset of C, but the culture of C++ programmers is completely different. It's considered bad style to use most of the C subset. And you can argue it's just to compete with Rust, but if code gets past the Core Guidelines checker it's mostly memory-safe.
Time will tell, but I suspect C++ with Core Guidelines could be "good enough", hence superior to Rust in the Gabriel "Worse is Better" sense. For $DAYJOB, developing products with security requirements, C isn't really in the running because it's inhumanly hard to use in this domain.