Direct, documentary evidence from the time - WA's corporate affairs officers on unions and incorporated associations
This November, 1991 memo from Peter Richards, the Assistant Director of the Legal Division, WA Corporate Affairs Commission defines a trade union as a "combination for regulating relations in employment". Any entity setting out to do that is ineligible for incorporation under the Associations Incorporation Act.
Any combination for regulating relations in employment can't be incorporated under the incorporated associations act. It can remain as an unincorporated association, or it can acquire corporate status under the trade unions act.
A lawyer at the time should have known that. So should today's TURC.
Julia Gillard was given substantial benefit of the doubt in the TURC's interim report. But the Commissioner was very clear, if it can be shown that Ms Gillard "deliberately ignored" certain matters, she's in strife:
If she deliberately ignored the matters described, she was party to Ralph Blewitt’s deceit. The more probable view is that she would have been careless, not deceitful. She had no motive to be deceitful. (para 60, AWU WRA report)
The Commissioner doesn't say she needed positive knowledge of the deceit in the AWU WRA application for incorporation, rather it's sufficient for her to be a party to the deception if she ignored things that should have set alarm bells ringing.
Julia Gillard knew of the WA Corporate Affairs Commission's objections to the AWU WRA, yet she continued to argue the case its incorporation. She vouched for its bona fides and stated that it was not a trade union, that is it was not "a combination for regulating relations in employment". On any read of its Objects (drafted by Ms Gillard herself) it was just that.
Here's more from WA Corporate Affairs official at the time, Ralph Mineif.