The whole speedblitz argument is a joke.
Franklin, at full potential, is not "Human". Period.
He is Ulti-Man. Equal to, or more powerful than the Celestials. An Abstract Entity.
The most powerful being in the universe/multiverse.
Being the most powerful being in existence cannot be contained in flesh and blood. Cannot travel as a human through space, time, realities.
His power is immeasurable. Strength immeasurable, durability immeasurable, intelligence immeasurable.
So, the comic goes like this...
Superman does his gay speedblitz, Franklin does not react as Superman pounds away. It looks like Supes was faster than Franklin's thought or reflexes.
Then, all the fanboys get excited as they turn the page of the comicbook.
All jaws drop. On the next page, Franklin is still just standing there, watching, as Superman's arms and legs begin breaking down into stray atoms.
All Superman can do, is look up at Ulti-Man, and mumble one sound:
Erg?
Franklin giggles as he punches Superman's funny, wobbly torso right out of this reality.