What is the standard of review of Commissioner Dion’s decision to reopen a case?

Although the appellants had argued that Commissioner Dion’s decision was reviewable on a standard of correctness, the Judge held that the standard of review was reasonableness. He reasoned that absent legislation requiring that a decision be reviewed, a non-adjudicative body’s decision to reopen a case is discretionary and discretionary decisions attract a standard of reasonableness according to Dunsmuir v. New Brunswick, 2008 SCC 9, [2008] 1 S.C.R. 190 at paragraphs 51, 53 [Dunsmuir].