The statement "there is no memory safety without thread safety" does not suggest that memory safety is sufficient to provide thread safety. Instead, it's just saying that if you want thread safety, then memory safety is a requirement.
No, they don't. They're using a different meaning for "thread safety" that's more useful in context since they do ensure data race safety - which is the only kind of thread safety OP is talking about. By guaranteeing data race safety as a language property, Java and C# are proving OP's point, not refuting it.
