Didn't they also own a condo in Toronto? If they truly felt unsafe they probably would have gone there instead.Just a thought: Is it possible, that HS/BS suddenly thought, their home wasn't safe for a meeting with the builders of the giant and very expensive new mansion? Is it possible, that BS was afraid, they would be bugged? Is it possible, BS felt more safe in his own office at Apotex (whether rightly or wrongly)?
IMO, the sudden change of location must have meant something, especially since the events might have started with the meeting.