I don't think Steve Unthank has a case because jehovahs witnesses do not engage in specific child related work according to the Act. they don't have separate sunday schools. Wherever children take part in religious activities adults are not excluded - the activitities apply to adults and children. If this goes to court Jehovahs witness lawyers will be able to refute his claims very successfully imo.
the theocratic ministry school does not exclude adults - this is not a child only school - so the Act would not apply here.
likewise the ministry, meetings, mentoring schemes. The Australia act is very similar to what we have here in the UK. What I have read at least is the same. I would be interested to know why many here who have read the act are so convinced that Jehovahs witnesses are contravening the Act as to me they don't even fall into a grey area?
edit: although I do admire Steve Unthank's tenacity