I didn't say you can't write useful software in C++. I said that C++ software is not, in general, memory safe. Sometimes the benefits of a particular piece of software (for example, having an excellent production-grade optimizer) outweigh its drawbacks (for example, not being memory-safe).

I don't think you'd find a single LLVM developer who would claim that LLVM is memory safe. Giving invalid IR to LLVM and not running the verifier frequently segfaults it, for example...