It seems rather ridiculous to me that such a person was even able to apply and to be accepted to a Teachers College. It seems that the system has some serious problems.

JCU is not a teacher's college, but has a college of education among dozens of others. You can apply all you like to study to become a teacher, since no criminal record checks are required at all simply to study. But the catch is, in Australia, that practical work is a compulsory part of the course in order to graduate as a teacher (typically a minimum of 100 days work experience is required over the four years of the Bachelor of Education). Criminal record checks are done as part of the work experience hiring process. If you can't get hired because of a failed check, you have the option of transferring into, say, a Bachelor of Arts with a major in Education or whatever. You won't graduate as a registered teacher however.

The system does not have serious problems. People regardless of their criminal history should have no problems being able to study, since it helps in the process of building their self esteem and confidence back up, and obviously this has important implications for the rehabilitation process. Actually doing work experience with real and possibly vulnerable people is another matter.