Mitch4 sends this in: “Two and a half hypotheses:
1) The intended cartoon was indeed pulled by the editors, for being in one or another aspect beyond the limits of acceptable — political or personally impolite etc.
[1.5 Exactly as reported, it was pulled for being “too humorous” — nah, very unlikely, but maybe this was literally what was stated to him though intended to convey #1.]
2) Nothing of the sort happened, and this is just a variation on “the cartoonist took a day off from drawing”.”