The reason you don't get to click on the head to respond to the secondary message (not the first one - if you take the time, you can see their hat if you click on the initial one) is because of all the messages they would receive if you COULD.
The second message, to like 99% of the server that gets it, is "better luck next time,' sent to people who did not get into the event and wanted to. The vast majority of the messages sent back at that point would be things like "I hate u admin" and "Please host sumo next round" and "I want free hat."