This has been a law since 2010 so it is not like you didn't know about it. OK you really thought the "private club" thing was going to work?
Having been involved in organizing several of these events I can tell you the FIRST thing you do is your homework.
My personal feeling is that the people involved did not care and decided to go forward with it anyway.
Hopefully this event did not give conventions a bad name. We have 2 coming up one in Orlando and one in Daytona. Florida does not have any laws restricting vaping indoors. So VAPE ON FLORIDA!