Ah.
That's what we thought too.
My response card story was a bit different. My 92 year old great-aunt, who happens to be my mother's godmother as well, phoned up 3 weeks before the wedding to know if some guy who once knew the family could be invited. i wouldn't know him if I fell over him, so I said no. My mom got caught in the middle because my aunt was soooo used to getting her way. Marc and I pointed out that just because you're venerable and OLD doesn't excuse rude behavior, and it didn't matter how old she was, or whether telling her "no" would break her heart, it was still tacky to invite someone that close to the wedding.
I don't think she ever forgave me for that... She held it over my mom till the day she died that my mom didn't invite some uncle to HER wedding, and that was 30+ years ago.