I'm not sure if its lack of faith in Zampa, or total faith in the seamers. I think Maxwell only bowling 2 could be considered questionable as well, even if his overs today weren't great.
I don't rate NCN or Faulkner at all, so it's easy for me to say that it's insane to expect 4 overs out of them, but Smith bowled NCN out in every game, and the games Faulkner didn't bowl out, he bowled 3 overs, two at the death, with MMarsh bowling the other over. He's clearly got faith in Haze/NCN/Faulkner to bowl out. If Watson had got thumped all over the pace, he would have bowled less with Zampa picking up the rest. But that didn't happen, so Zampa couldn't pick up any overs.
People are saying Zampa should have bowled the 15th. Yeah maybe. He should have bowled the 7th over or whatever. He didn't start bowling until the 10th. Faulkner got a bowl in the 7th. The early success of the seamers strengthened the faith in them, which cost Zampa and the team