I'm not an expert by any means so please don't hold me to this. TWOV i.e. Transit Without Visa was a program whereby people who would usually need a visa to transit the US would be allowed to transit without a visa. There was another program called International to International (ITI) again which allowed people to transit without a visa (but only through one US airport).

Looking at this and your account I don't think that you were denied entry to the US, just accorded some extra attention by the CBP. If you were denied entry you would have been sent back to Australia without a stamp in your passport. No deportation, no denied entry.

But to be safe just use your Canadian passport, no Visa Waiver form no problem.