You got me. I have no sure answer, I can only speculate. The referred input voltage and current noise is a black box model of an IDEAL op-amp with added current and voltage noise. Ideal op-amp has infinite input impedance.
In real life( not the model), the noise current actually comes out of the input of the op-amp. The current become a voltage through the external impedance. Remember the op-amp has high open loop gain, the output will change to make the input goes to zero. So if the input noise current create a noise voltage, the output of the op-amp with generate an output to neutralize the noise so to make the input back to zero.
As you can see the article I posted in post #9, equation 3.3 gave Req=R1//Rf only, the input impedance is not in it. That's is also what I studied before.