I voted "Not Rude". While showing up at a wedding that one was technically not invited to, it's not like he is someone's ex and was specifically NOT INVITED!!!!1111
I guess when one of my sons eventually get married, I'll have to leave a list at the reception of people who are allowed to drop in for 10 minutes:
the band Queen
Any classic rocker
and, of course, Alan Rickman, Jeremy Irons and/or Hugh Jackman
but - what if I miss one who happens to be passing? What if Sean Connery hears the pipes (which we will have whether my son wants them or not) and I didn't specifically put him on the list??? Do we turn him away?
Not rude - totally fun - and 10 minutes of Justin Bieber beats 10 minutes of my MIL any day.