All right. I haven't thought as much about the proposed section 494 as about the rest of the bill, but I'll try to give an answer.
I think that in the bill as it stands, the requirement that a person be found committing an offence has been interpreted in others parts of the Criminal Code to mean there exists a reasonable belief that a person is committing the offence. Mr. Preston has suggested expanding that to reasonable grounds to believe that an offence has been committed, even if the person exercising the power doesn't see it themselves.
I don't think the danger you point to can be avoided entirely in practice, but stereotypical beliefs about a person's behaviour, it seems to me, could not form part of a reasonable basis on which to exercise the power.
I guess that would be my suggested way of controlling it. So if the person exercising this arrest power says “Well, I thought the person was shoplifting because...” and then gives several reasons, and some of those reasons include stereotypes about a certain class of persons, then I think those could not count as part of the reasonable grounds, and that reasoning might affect the lawfulness of the arrest that was made. That's my opinion, but I don't think there's any way to eliminate that entirely in practice.
Mr. Preston might have something to add to that.