Loop amplitudes describing the transition of an electroweak vector boson into QCD partons are important ingredients for precision phenomenology at the LHC. Existing compact analytic results are commonly expressed in the massless spinor-helicity formalism using a leptonic current in place of the vector-boson polarization vector and, therefore, appear to describe only its transverse polarization states. Exploiting the little-group covariance of these amplitudes, we show that they actually retain the full polarization information of the massive vector boson and can be promoted to spin-covariant amplitudes with open $\mathrm{SU}(2)$ indices in the massive spinor-helicity (or spin-spinor) formalism. In particular, this allows the ``missing'' amplitude for a longitudinally-polarized massive vector boson to be reconstructed through simple replacement rules, avoiding entirely new loop calculations.