Considering that even the touch judges had not got into position yet, he had every right to yell at the ref.
The Cowboys would have rushed back as soon as the kick had been taken. Hicks would have waited to see if the kick went over, and then, as he jogged back (again, he has every right not to run) got a drink from one of the trainers. At this time, the Cowboys could have been a good 20 metres in front of him before he even noticed.
Ok, so he should have had the wits to know it would have been a short kick off, but they did it awfully quickly- too quick considering the touchies hadn't got back yet. It was a bad decision from Clark that probably ended up costing us the game, as well as the others in that set and before hand.