You definitely don't need a Carnet for Canada or the US.
"USA, Canada, Mexico and European countries do not require duty, Customs bond or Carnet to import personally-owned 'tourist' vehicles as long as they are re-exported within liberal timeframes, usually 6-12 months."
From Canada Customs website:
"At the time of importation of a conveyance or baggage into Canada, a security deposit may be required at the discretion of the customs inspector to ensure that all of the conditions of importation will be complied with. While a security deposit may be in an amount equal to the duties otherwise payable on the goods, a nominal amount is often satisfactory. Normally, security deposits are not required when visitors enter Canada for short periods of time for holiday or leisure purposes.
When a security deposit is deemed necessary for goods temporarily imported, the customs inspector will issue Form E29B as a control document. Any such security in the form of cash or certified cheque is refunded to the traveller by means of a Government of Canada cheque, which is forwarded by mail after the items are exported from Canada under customs supervision. While it is not necessary to export the items at the same customs office at which importation was made, Form E29B must be presented to customs along with the goods for comparison and acquittal. The traveller will be given the receipt copy of the duly acquitted Form E29B.
Canada is also a contracting party to the Customs Convention on the Temporary Importation of Private Road Vehicles. In accordance with the Convention, an international form called Carnet de passages en douane can be used instead of Form E29B, when a non-resident imports a private road vehicle for health or pleasure purposes for a temporary period not exceeding one year. The form is available in the importer's country of domicile through automobile clubs and other authorized outlets."
The fact that Canada Customs do accept the Carnet as security may be what has confused the consulate in Sydney.
But, the bottom line is that Canada would normally not ask for any security or for a Carnet as long as they have no reason to suspect you intend to leave the bike in the country.
'One world, two wheels'