Who cares about the age? She isn't 18, 19 or 20. She is 27 years old, and knows enough about life to understand what she is getting into. She likes Jon, and if they want to get married, by all means. Let them be happy. Way to many people who are close to their same age end up in divorce. So if they find happiness in this crazy world, so be it.
As for John and his ramblings, Jon always plays by the people whoever pay him his paycheck. Such is life. Calling people names was just uncalled for. But then again, John was always one of just liked to push the buttons on whoever. Shock value.