Explanation:
"Incumbent" means the responsibility that any person hold in the office
"Reliable" means the trust one get.
Job analysis: Analyzing the requirement that meets the job title and organization's goal.
Since the presentation talks about the merits of the job, it is right a client enquirers about the reliability too.
A client or any customer considers "reliability" as the top most essential need
So We can convince the client by saying, "it is reasonable except for task inventory ratings using job incumbents"