When you have a party and when as the tweet says "Dear vandals, all Wikipedians are drinking beer so this is your chance to have fun!" It is really nice to learn that they did not only have fun while we were drinking beer.
The anonymous editors did not only edit during the party. There were 30% more edits that day and the next day topped an already great turnout. Yes, there was more vandalism then usual, but was it also 30% more?
It is gratifying when more people, new people find the courage to press the edit button and make a positive difference. New people will make Wikipedia their own and this will be part of the bright future Wikipedia has in front of it.