i can't even see the problem here if they were selling them for $0 profit. let's assume for a second they sold them for $5 each and that is the actual cost of production. would ben show the same hostility to individuals who spent $5 to make the poster for themselves?
that said, i'd think it was a silly response even if they were selling it for profit. do you really want to focus your creative energy defending your authorship of a white poster board with red lettering?