The Courier-Mail article pretty much correlates with what I'd been thinking. I didn't think he'd thrown her off, nor that she fell whilst they were intimate on the balcony, rather she was fleeing. The incident being five and a half hours after they met, and that they'd been seen drinking and talking on the balcony, would indicate this occurred much earlier. Perhaps she went back in around midnight and slept, and was awoken by GT assaulting her? Disoriented perhaps, the balcony seemed like the quickest exit to escape by?
Murder sounds like a stretch. Either way, he needs to do time.