Placement new breaks consts and references?

Following the discussion on my answer to this question, apparently:

the following code is allowed

struct Foo {
    int x;
};

Foo f;
Foo & f_ref = f;

(&f) -> ~Foo ();
new (&f) Foo ();

int x = f_ref .x;

but the following code is not allowed

struct Foo {
    const int & x;           // difference is const reference
    Foo (int & i) : x(i) {}
};

int i;
Foo f (i);
Foo & f_ref = f;

(&f) -> ~Foo ();
new (&f) Foo (i);

int x = f_ref .x;

Because of $3.8/7

If, after the lifetime of an object has ended and before the storage which the object occupied is reused or released, a new object is created at the storage location which the original object occupied, a pointer that pointed to the original object, a reference that referred to the original object, or the name of the original object will automatically refer to the new object and, once the lifetime of the new object has started, can be used to manipulate the new object, if:

• the type of the original object is not const-qualified, and, if a class type, does not contain any non-static data member whose type is const-qualified or a reference type ...

I can understand how a reference to f.x could be invalidated when f ceases to exist, but I don't see why f_ref should be invalidated purely because one of its members is const and/or reference and not otherwise: it was a refe