Company president: Grievance procedures should allow the grievant and the respondent to select a mediator who will attempt to work out a resolution.
Conclusion (However)
Beginning mediation fairly late in the process, as our human resources department proposes, would be relatively ineffective.
Evidence
There really isn't any evidence provided for the president's criticism. They open with a pair of concessions: grievence procedures should allow mediation, and mediation can be helpful. Then, they pivot into their criticism.
Evaluate / Goal
It's unusual for a Strengthen question to ask us to justify a claim that has no evidence to back it up. The pivot (however) away from the concession and into the criticism does give us something to work with, though. The president concedes that mediation is helpful, so why are they concluding that this particular HR proposal for mediation won't be? The only clue we get that might support that this proposal is an exception to the rule is the idea of "beginning mediation fairly late in the process." Predict an answer that connects starting late to being ineffective.