That's surprising. Tech is supposed to be Doug Lafavre (Dr Dew), the frame designer since way back when. But maybe Tech is a group of people, whoever happens to be awake at the time.
You need what's called a 30.0, although the Kona ones actually measure 31. The seat tube is externally butted - it is a 28.6 tube, but the external butting at the top takes it out to 29.8, hence you need a 30mm clamp.