NSW Termination Due to Poor Performance - Non-Compete Invalid under Employment Law?

Recent termination due to poor performance. During the time of perfromance management, it was found employee suffered a medical condition which contributed to his perfromance not being satisfactory.

Following granted paid sick leave and returning to work, the employee was faced with a 10-day turnaround performance plan. The first plan was not achieved and comment was made to superiors the length of plan was in his opinion too short a timeframe to complete or provide adequate responses. A written warning was issued.

A second 10-day plan was put in place and following completion of that 10-day plan and submission to superiors , it was considered to have not met the standard required and subsequently a Final written warning issue. A final 10-day plane was issued and subsequent meeting held where details of plan discussed, a final opinion was reached that it did not meet the minimum requirements and was subsequently advised at the meeting of his employment termination and granting 8 weeks notice.

Question: Given forced termination and subsequent longer than general notice period (employee is not in senior or executive capacity and was with the firm for 14 months), can it be argued successfully under Employment Law that restraint of trade or non-compete is invalid, given the employee did not met minimum standards reached at the company to hold down employment and thus should not be enforceable?