Earlier quoted context omitted.
Every GC language by definition are memory safe, memory safety in programming does not mean than accessing the same resources from two thread should be safe.
I don't know how it works in other languages, but accessing a partially overwritten slice in Go (as will happen in the presence of data races) can cause your code to access out-of-bounds memory. And as we all know, once you have read/write access to arbitrary areas in memory, you've basically opened up Pandora's box.
Go is memory safe, if not then Java/C#/Python/Ruby are not either.