Leigh (2007)- share based payment

The scenario in part c) is : “On 31May 20X7, Leigh purchased property, plant and equipment for $4 million. The supplier has agreed to accept payment for the property, plant and equipment either in cash or in shares. The supplier can either choose 1.5 million shares of Leigh to be issued in six months’ time or to receive a cash payment in three months’ time equivalent to the market value of 1.3 million shares. It is estimated that the share price will be $3.50 in three months’ time and $4 in six months’ time.” The requirement is:”explain how the purchase of the property, plant and equipment should be accounted for in the financial statements of Leigh at 31May 20X7″

I wonder why the model answer to this part only refers to the case of cash settlement in three months, therefore, there is a liability of $3.9m and $0.1m of equity. The model answer does not refer to the case “1.5 million shares of Leigh to be issued in six months’ time”, which may have fair value of $6m in 6 months time, which may be more advantageous to the supplier and the supplier may choose this option.
Please help me to explain that. Thanks!