Five players will miss Sunday's (AEDT) Test against Scotland with after being handed one-match bans by coach Ewen McKenzie – the other nine players received written or verbal warnings.
The entire squad has also been placed on a mid-week alcohol ban and must adhere to a midnight curfew for the final two weeks of the tour.
MORE: Wallabies problems bigger than Ewen McKenzie could have imagined | Six Wallabies cut after boozy night out
Horwill admits players were wrong to stay out until the early hours of Wednesday morning, three days before the Test against Ireland but believes the incident was one-off.
"I don't think there is a problem, guys have made decisions and they're being judged on those decisions," Horwill said.
"We want guys making good decisions but I think you're drawing a long bow saying there's a culture or a discipline problem.
MORE: Tevita Kuridrani cops five-week ban | ARU chief backs 'appropriate' Wallabies bans
"This is based on an individual event.
"... I think it's just made it very clear what's expected. There is no grey area, that's what is expected and what the team management want and that's what we need to abide by."
The Dublin drama and the five-week ban handed to centre Tevita Kuridrani for a tip tackle on Peter O'Mahony will severely test the Wallabies' depth against Scotland at Murrayfield.
The Wallabies lost 9-8 on their most recent visit to the venue in 2009 and also suffered a 9-6 upset defeat in Newcastle last season, but Horwill backed the new faces to get the job done.
"The focus now for the group needs to be putting in a performance against Scotland because obviously the last two times we've played we haven't got the result that we wanted against Scotland," he said.
"We have full faith in the guys that will come in to fill those roles to get the job done.
"That's what's expected, that's why we travel with a squad and we've trained with a squad all year.
"That's what we're about, if there's an opportunity that someone gets that they take it with both hands."