The difference between this and a lightspeed laser is that the latter, presumably, has its speed stated as being lightspeed. This is not stated to be "Mach 4.3-14.5k", these are calculated to be Mach 4.3-Mach 14.5k. Calculating additional speed off of a speed already calculated, not stated, is calc stacking. Almost this exact situation is laid out as being unacceptable in our page on the matter.
"Character A has a certain speed through a calculation. He can not dodge the projectiles from character B from 2 meter distance. But Character C can dodge them from 1 meter distance, so character C has to be twice as fast as character A."
As for Pain, Pain is not calc stacked. He is scaled.