Sadly they don't.
Reasoning:
This is the result of a clash between Saitama AND Garou's Serious Punches, so it can't be scaled entirely to either one of them. You might retort to that with the argument that you should just divide the result by two, and while I can agree to that on the AP department, there is another issue that complicates that with Speed: Blast and his team.
The feat is the result of Blast and his team diverting the explosion, altering its vector and warping it as far away from Earth as they can manage. It is not the natural course that the impact would have taken had it been allowed to happen unaltered. Blast and his team either just altered the vector so the explosion would go to a single direction, which would already dramatically alter and increase the speed of the explosion, or they also folded space and warped the explosion away, in which case the speed is completely unquantifiable.