...and those are hardly the only variables.
Using those same gas laws, filling the ball immediately before submitting will give much different results than if the balls were filled, then stuck in the hold of a bus, then filled again. Filling a ball warms the air...potentially a lot.
There’s also leather stretching from being wet, and changing the volume.
...and no idea when the measurements on the Colts balls were done - reporters have noted that they are unable to verify that.
My calculations are (as I'm guessing you know) derived from the Ideal Gas Law. And pumping a football with air sure ain't an "ideal" situation!
I do think my calculation has some merit as a guideline. However, it wouldn't (and shouldn't) be accepted as hard proof. The only way to be sure here, from a legal standpoint, is to repeat the entire process under the same conditions as existed on that day.