Toyo sidewall cut and replacement decision

Have a sidewall cut in one of my Toyo Open Country A/T 2 Xtreme (295/70R18) that's down to/through the polyester cords, so it definitely needs replacing. Tires were manufactured right at 6 years ago, but still have ~10/32" of tread depth (new was 16/32") with pretty even wear.

Question is, given the age and wear should I just go ahead and replace the set at this point? Feels like replacing the cut tire with a new one might just be throwing good money after bad.