Another condition of employment is you must buy the type rating from the training provider in Australia nominated by your airline.
A condition of employment in this context is part of the bargain, ie: it is a part of the contract between the employer and the candidate.
They have offered to do X if you do Y. If you do Z instead, it is non-performance of your part of the contract and there are a range of remedies available to them.
I can see good reasons for the employer to require the training be done through a particular facility or trainer, and I am sure you can too.
I can't find anything in my old notes/texts that would give you the answer you want - sorry.