I could agree to that if the people who claim it would at least put it in their definition. But as it stands it indeed is a boolean. You have to give a definition of something like:

"Memory safety denotes the degree to which a programming language guides and protects developers from memory‑related errors—ranging from minimal, manual checks to comprehensive static and runtime enforcement—through mechanisms like strong typing, ownership or borrow checking, and garbage collection."

And then also include modern C++ in their lists. because by all accounts it is memory safe by that definition.