In relation to the first question, it may be that the client’s position is redundant.
If this is the case, the client may take action against ‘Employer A’. This should be emphasised to the client to avoid confusion.
In relation to the second question, the issue is whether objectively the tasks to be performed under the new role fall within the scope of the duties performed under the old role: Szanto v ISS Facility Services  FWC 3270
Factors suggesting that the role is not a suitable alternative include:
Conversely, if the employee was originally employed in a position which involved a very broad range of duties and a measure of uncertainty, it may be that even a notably different role is still a ‘suitable alternative’- Szanto.
Application to client’s case:
In relation to the case at hand, the role offered was clearly not a suitable alternative due to the significant change in the nature of the work (from a mixed commercial and technical role involving a broad range of activities to a wholly technical role), the dramatic reduction in the skills and qualifications needed, a potentially lesser opportunity for commissions, and the change in location of the work.
As a consequence the client’s role was genuinely redundant.