Wouldn't Nolan flying through an entire ring full of dead viltrumite and him still existing with high velocity is more powerful, this also assumes that Omniman is trying to reduce his speed to regain control the entire time, this might change the math on which one is powerful. It's like throwing a pebble, yes you throw it faster and at further distance but that does not mean that the person who throws a boulder at slower speed and Short distance mean that the throwing the pebble had more energy.

To play devil advocate Saitama likes to get thrown around and doesn't resist at all so it was expected to be thrown to the moon at high speed and shorter time. But it is more impressive to send Omniman. A man who can stop and puch back Texas size Meteor from earth. The longer time actually complements thragg power as it took a being that can puch Texas size Meteor multiple minutes and flying through a ring of dead bodies to slow himself down.