Stanley Park is a big place, as big as the whole of downtown Vancouver. The murder happened on the west side of the park, on the seawall walkway. You'd get there by either walking or driving from the West End residential neighbourhood. There's a quiet road that encircles the park, so it passes all the park amenities like restaurants, viewpoints, parking lots, major trails, the aquarium, etc.
Then there's the busy causeway that funnels traffic from the commercial downtown, to the north end in order to cross the Lion's Gate bridge. The quiet Stanley Park drive passes over top of this highway. I don't know where exactly the emergency stop was where the taxi let him out, but if you were intending to go somewhere in Stanley Park, that'd be probably the worst way to do it. It would only make sense to get off there if you wanted to walk to the bridge. It was about an hour before dark.
People do like to view the bridge and views and take photos, etc, but it's also the most popular suicide spot in Vancouver. Bodies might not always be found, there are tides, the bridge is very high to let ships pass under. Seems to me, reading between the lines, this is the police theory. His age is also a factor, tragically a high risk time of life for being, perhaps, suddenly overcome with despair and not being able to ask for help. For eg, a failed love affair, anxiety about school and career, etc. There was talk a few years ago about a mysterious spate of missing young men in Vancouver, when I followed up the cases, almost all had been eventually found and were ruled suicides.