Regent Park has FreshCo right in it.
This grocer's customer base is basically going to be Corktown & the Distillery, further north FreshCo will be preferred and further west, No Frills. especially since it's a high-end market. Most customers will be walk-ins from the immediate area, which until now, has had a relatively small population.
There are a bunch of projects which will reach occupancy in the next 2-3 years in the immediate area that will probably roughly double the population of the area though, so there will definitely be a market then. But in 2015/2016 as the first buildings in the West Don Lands were occupying, this area was really not dense at all and couldn't rely on adjacent areas which already had grocers which would draw customers.
Geography is also an issue with the Gardiner and Don River meaning there will be basically no customer draw from the east and south.
Ultimately No Frills is less than a kilometre away anyway from here. Honestly, I'm surprised there is a grocer open now at all. There are a lot of areas in the city with far, far higher densities without a significant grocer presence still (entertainment district!!)