Answered: NEC TSC: What are the implications of an Employer's common law repudiation of Contract ?

The key point for me here is that there are two things (at least) being intermingled and it is important to separate them.

There are a number of way to bring a contract to an end: 1) termination, a contractual right and process, 2) repudiation, a common law process, 3) completion, a contractual right ie you have done everything you are obliged to do, 4) frustration, a common law principle sometimes clarified in the contract, etc. These are all different. Frustration as a means of ending the contractual rights and obligations is not a termination. Similarly a repudiation is not a termination. The law, process and effect are different (albeit they end up in the same general place).

In your example you mix the two saying the adjudicator decides the termination was lawful but the contractor affirms. You cannot affirm a termination only a repudiation. Without affirmation the repudiation does not take effect and the contract continues. It is only where the repudiation is accepted (as a positive act) that the contract actually comes to an end.

This is not a simple area and will be highly driven by facts. You really should take some detailed advice.