I think that the answer suggesting asking for payback was actually intended as a joke. Or if not a joke, as such, then an outrageous response to an outrageous request. Tit for tat.
In the US and some other places there is a card game called Poker that is normally played in "rounds of betting". If a person bets X then the next person has to bet X or higher. If higher it is called "raising" ("raising the bet", "raising the ante"). Often you raise the bet quite a lot to force other players out. They aren't willing to equal the bet ("call the bet"). I think that the answer you pointed to took the request for authorship as a "bet" (or an "opening") and the response was just "raising the bet" to force the first person to retreat. The suggestion was so ridiculously high that the other person would "fold" (leave the game).
That should ease your fears, I hope. On the other hand, reacting by referring to "asshole professors" won't make you popular with your faculty. Rage seldom wins in Poker, either.