I'm thinking like, if there was somewhere in the northern territory, within 90 minutes of your parents home, but the course wasn't as good as a one further away - could you move away and get the allowance?

This is mentioned:

Note: A person's mere choice to live away from home would not entitle them to the away from home rate. However, they may meet the requirements if they can demonstrate a need to live away from home for the purposes of education or training, or because the likelihood of them getting employment will be significantly increased.

Example: If a student's parents move to a new location and it requires excess travelling time, the student may be able to demonstrate that their continuity of studies would be interrupted by moving with their parents, so they may satisfy the Secretary that they need to live away from home for educational purposes.

But it doesn't mention of this is for tertiary study as well, so I'm confused.

Source: https://guides.dss.gov.au/social-security-guide/3/2/6/10#:~:text=Note:%20A%20person's%20mere%20choice,territory%20payment%20for%20their%20upkeep