Stereotyping is not a necessary component of the section 15 violation. Discrimination is defined as any imposition of a burden or denial of the benefit that reinforces, perpetuates, or exacerbates disadvantage. That is the test.
Deciding whether that prima facie violation of section 15(1) is then justifiable because there is some type of rationale—for example, the protection of people with mental disorders—is then done at the section 1 component of the Oakes test.