He was said to have boasted of the sexual prowess of Belize men compared with British men and made suggestive comments to them.
"The comments he was supposed to be responsible for are frankly amateur," Mr Norman said.
"It's difficult to say this could be described as anything more than laddish.
"It's not something that gives rise to particular anxiety of a criminal act.
"Why on earth should the school or the tour company be liable for this contact? There is nothing to say this is likely to happen."
According to the girls, the man barged into the room that was yards away from where their teacher slept but he started off by "being nice".
Mr Justice Mackay said: "There's a bit of drinking then there's a bit of spin-the-bottle. The party was taking pains to keep the noise down."
Mr Norman suggested the way the scenario developed was irrelevant because the teacher and two adult leaders on the trip had made "well thought out arrangements" to ensure the girls' safety.
"There is nothing to say this is likely to happen," he added.
The court heard checks had been made on the resort before the activity trip but there was no CRB-type system in Belize to check the records of anyone working with the children.
Earlier this week, the teacher who was with the trip said she would have heard the girls if they had shouted out.
She said she was 15 metres away when the attack happened.
"Noise travels incredibly well and had anything been amiss, the leaders would have been up and running, as I would," she told the court.
Asked about the checks made on the man, she replied: "You can't suspect every man of being a rapist."
The two girls told the court they had suffered post-traumatic stress disorder since the attack.
Mr Justice Mackay is expected to reserve judgement.