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.
It's saying the opposite – that if you want memory safety, thread safety is a requirement – and Java and C# refute it.