I mean it's far better to stick the grocery store on the ATC side of the tracks in terms of residential traffic. There are more apartments surrounding the ATC than downtown proper. You have the new condos being built to the West, the Cortland Bull City Apartments that replaced the old dilapidated hotel, Whetstone apartments by the bus station, the bust station traffic in general, Willard Apartments, Bullhouse Apartments, Van Alen Apartments, and 2-3 other new apartment buildings going up by Ciderworks right now. Not to mention just the general office traffic picking up quick things on the way home from ATC, 555 Mangum, Avalara, etc.
While yes there is some residential on the other side of the tracks downtown, the ATC side has a wealth of footsteps that will keep a grocery store there bustling without batting an eye.