There is a lot of information about this station in the
City report -- the rationale seems to boil down to "this area has a lot of development, so it needs an RER station". The prospect of the DRL isn't even mentioned. although the Waterfront Reset LRT is.
The Barrie RER line will have a certain utility as a "relief line" in that it will connect to Line 2 at the new Davenport station, and the Crosstown at Caledonia, and maybe eventually to the Finch LRT. So for some with origin.destinations in the Spadina-Front area, it might be useful as an alternative to riding the Line 1 subway to Union. But that feels like a kludge to me, and it doesn't impact the DRL at all.
- Paul