Mind telling a bit more about what this is about? I would love to work in Bitcoin for a living and I would most likely solve your funny riddle within an hour for the fun of it but I find it rude to not say anything about what this is about or show a link from coinbase itself to it that would proof that you actually are from coinbase. What do you need? I mean do you need language skills? Do you need global distribution? Why ask the time in a certain time zone as a hard discriminator? You believe that you get an indicator of how fast people are via this? People that know all the answers to your questions are certainly capable of training and submitting the test from a different ip/machine, so you will not get a timing neither.
Also to generate a 1BASE-vanity address you might have bad luck and it takes an hour alone to install vanitygen and generate that address. I wouldn't like to jump through hoops and loops just to be sorted out because I was too fast aka solving your time lookup last is considered wrong.
… and what has sorting letters to do with customer support??