Right; I elided from one to the other to give a calculation of interest to the thread topic. (I had thought I had written it sufficiently clearly? What should I change?) The "sol" case is still at the hydrogen-bomb level—but not 9 orders of magnitude beyond it.
Because there's few reference points with which to interpret numbers on the scale of 10^12 Watts/meter^2, and it doesn't fundamentally change the XKCD outcome anyway (from the human perspective). I thought shifting it to nearby stars made it topical to this thread, where multiple comments are asking about the impact of galactic supernovae.
(That's the less important part of my comment, and I'm not sure why people latched onto it! The important part is that supernovae are >7 orders of magnitude slower than hydrogen bomb explosions).
Well for starters you did not say that supernovae are >7 orders of magnitude slower than hydrogen bomb explosions, and it sounds an awful lot like you misinterpreted the original statement as referring to a supernova 4 lightyears away, which would coincidentally lower the value by about 9 orders of magnitude.
GP and XKCD are talking about a supernova from the Sun, you're talking Alpha Centauri.