Member const reference is bad design?

[baudolino]

"If a temporary object is passed to a constructor (by const reference) and bound to a member const reference, the lifetime of the temporary isn’t expanded and the reference becomes a dangling reference (with no diagnostic)."

from http://herbsutter.wordpress.com/2008/01/01/gotw-88-a-candidate-for-the-most-important-const/.

If we have something like this:
class StringHolder
{
public:
StringHolder(const std::string& str): m_str(str) {}

const std::string& string() const { return m_str; }
private:
const std::string& m_str;
};

1)StringHolder str(std::string("tmp_str")); //this is bad, accessing str.m_str is undefined

2)std::string tmp_str("tmp_str");
StringHolder str(tmp_str); //this is ok


In this case, isn’t this an example of bad design to have a “const &” member? Because you’re not sure how it will be constructed.
How can the creator of StringHolder class be sure that its class would be correctly used (i.e using 2 form, not the first one)?