Should SF.7 be less specific on how the namespace is modified, ban other mutations in .h files?

SF.7: Don't write using namespace at global scope in a header file

the global namespace can be modified as follows

// foo.h
namespace foo {
    using namespace bar;
}

I've assume this rule intends to ban namespace mutations (other than straight additions), but but as written allows this. Should this be disallowed?

I suspect this was written to allow use of namespace aliases in functions scopes but missed this case.