I see. You are comparing Blue Marvel to KC Superman instead of Superboy in order to use AB logic to make your case. So since Conner is only knocked completely unconscious as opposed to being killed, you have made a case that BM would not kill Conner with a single punch; something that no one has seriously claimed, if claimed at all.
Now for one, you may want to compare apples to apples, which would mean comparing a blow to a blow. From the standpoint of measurements of force, Blue Marvel is expressed to have moon splitting power. So we can move away from Arkansas. The moon is a little more than ¼ the size of Earth (assuming the book is referring to an Earth sized planet) and 1/80 it's mass, and it would appear that splitting an object in two with a blow requires significantly more force than moving it, making up for the difference in mass.
Now if I use similar AB logic, then consider that BM has evenly matched Earth-13034 Hyperion who catches an Earth sized planet coming at him at 500,000 miles per hour and holds apart two Earths, each backed by the force of its respective universe.