If you meant that how it reads, if you can shoot 1.5 MOA groups standing, you can win the national championship and set the all-time record. I doubt that many hunters can put 50% of their shots into 6 MOA from the standing position.
I did say "assuming a good marksman with a good rifle and ammo", but I agree 1.5 MOA groups standing is being generous, but it served the purpose of showing the need to account for group size when figuring out the best zero distance. Here's what that looks like using your 6 MOA group size.
With that group size and the same scenario from my prior post the optimal zero distance drops to just 122 yards. This demonstrates the folly of setting zero distance based only on the vertical trajectory of the bullet, but that's the only tool most ballistic calculators offer their users, and from decoydog's last post it looks like he's fallen into that trap.
There is no one answer to the OP's question. It depends on trajectory and game. Also the game does not always stand around while you use your rangefinder and turrets. A flatter trajectory lets you shoot quicker and hit better…
I agree there is no one answer to the OP's question, but a full featured ballistic program can illuminate any likely scenario. If fact, the above image shows that if you shoot 6 MOA groups then a flatter trajectory offers little in the way of shot placement, and many here will tell you terminal bullet velocity / energy is not a substituted for good shot placement (unless you're shooting a 20mm canon).
The takeaway is that a person should know their group size from likely hunting positions. If it's 6 MOA off-hand standing then, given the example scenario, limit shooting that way to 122 yards, but if you can do 1.5 MOA groups with a rest, then you can shoot out to 205 yards without adjusting sights. Further than 205 yards and you need to consider wind and maybe dial-in the sights to get good shot placement.