That poster is hysterical. Really, I doubt anyone with G.I.S. would get their feelings hurt, because they can't recognize they are using the punctuation incorrectly.
Generally, people who do the apostrophe thing wrong also can't get homophones (their, there, they're), things like lose and loose, or spell words like definitely that it seems like no one can spell. For some it's laziness, but for a lot of the people I know who do this, it's a form of a learning disability. I bet if you asked, a lot of these people would say they are not good readers or writers.