C++ is insecure in memory and has infinite unexpected behavior. Rust, on the other hand, does not compare with it, as it is safe. Linus doesn't like C++ because it sucks.
Yeah, Linus doesn't like C++ because of the abstractions and complexity, which Rust doesn't save us from. He'd rather have a less secure but simpler (and more widespread) language. That said, it's great of him to stay open minded and opening the doors to Rust in the mainline tree.
Performance/reliability issues caused by programmers can be found and rectified. Performance issues caused by compilers may not be replicable even between builds.