A series capacitor will block the DC phantom power and turn the mic off, yes.
But it might not block the pop. Blocking the pop from a microphone is more tricky than most people give it credit for, especially when it's phantom-powered like that. That's why I suggested an L pad. Sounds like overkill, but in a professional studio they pot the mics up and down for this reason.
If you try the cap, put it in series with the mic (forget the isolation transformer for now), and switch a resistor in parallel with the cap. I can't tell you the exact value of the resistor, start with maybe a 220Ω resistor and a 10µf cap and see how that works. You will be balancing the current requirements of the mic against the charge time of the cap.