" I don't think an entire guild should be held accountable for 1 person"
Holding the guild accountable for the one, has long been the practice on Siege since the earliest of days. You are the company you keep. Guild reputation used to, and still should be, paramount. If someone in your guild is not representing your guild as you expect, then boot them. Guildless people used to be Kill On Sight, which is one of the reasons NEW was founded. Guilds who could not keep their people in line suffered accordingly. NEW was special.