I'm not saying that the success of this extension rides solely on whether Twin Brooks gets a station and ridership, but the larger issue of making Edmonton a more transit-oriented community and less car-dependent does. Running trains through a neighbourhood for which the closest point to actually board the line will be 32 blocks north (Century Park Station) is senseless. The train will be traveling right through the neighbourhood, but without a station, the line does zilch to improve sustainability and eliminate car trips to/from Twin Brooks.
The other big issue, as I've pointed out, is that if Twin Brooks doesn't get a station, residents are almost immediately going to start bellyaching that their neighbourhood is "negatively impacted by a line they "can't use." They'll be grousing about the crossing gates being down all the time, and trains passing through, and the overhead wires, insisting that their neighbourhood is somehow paying the price for a line that doesn't serve them at all.