ok so what happens after the offer closes

Well what about this scenario:

Since it is an unconditional offer, Zinifex is currently taking acceptances of its takeover offer, AND getting its broker to buy on market at the same price.

Now suppose Zinifex closes the offer on Friday afternoon.

Could Zinifex then have its broker buy shares on market on Monday for whatever price they trade for, say, 80 cents ?

I don't see why not. In general, companies can buy shares in any other company they like up to a 19.9% holding. Its not inconceivable that Zinifex could pick up 15-20% of AGM next week at prices well under a dollar. Could be a smart strategy ! But is it legal ?