This protester’s charges have been resolved by their acceptance of an ‘adult caution’, so they won’t be facing any more legal proceedings over this incident. More details in my comment here: https://aussie.zone/post/30509630/21880036

The public prosecutor would need to prove the shirt was used to “menace, harassment or offence”. Even a mediocre defence lawyer should be able to have the charges thrown out.

A good lawyer will take it to the High Court of Australia and get the legislation thrown out.

OP is lying - she wasn’t even charged. She was given a warning.