  We expand on the methodology outlined in previous work that predicted the
width of an antineutrino wave packet emerging from a beta-decaying nucleus, to
the case of a neutrino from electron capture decay. Based on this result, we
also respond to a recent Beryllium Electron capture in Superconducting Tunnel
junctions Experiment (BeEST) paper which utilizes this previous work in forming
their measurement of the neutrino wave packet width. According to our
interpretation, the direct limit on the neutrino wave packet width from
electron capture decay ($e^- +
\mathrm{^{7}Be}\rightarrow\mathrm{^{7}Li+\nu_e}$) using the BeEST analysis
should map to $\sigma_{\nu,x}>6.2\,\mathrm{pm}$ while our theoretical
prediction is $\sigma_{\nu,x}\sim2.7\,\mathrm{nm}$.
