The speed of the meteorite is not being scaled to the size of the planet, but to the atmosphere scaling from the direct view of Alabasta
I'll do the calculation now (using the first panel):

Panel height = 381px Alabasta = 3226.8km for the length = 16px 2atan(tan(70/2)*(16/381)) in degrees = 2.27981118 degrees
In Angsize, the distance = 81,085km
at 17km/s, it would take 4770 seconds or 1.325 hours to fall to the ground.
If that's the case, Law must've brought out a lawn chair to chill while waiting for the meteorite to fall down. Perhaps read a book.
On a serious note, even if we took the 2nd panel (since it is possible that the view I calculated could potentially be in space), there are still tens of thousands of kilometers between the view and the ground.
Law, who was trying to escape, would not have sat idle to wait for Fujitora's attack or over 2 minutes, let alone over an hour.
In 120 seconds, the meteorite would have fallen 675708.333333m/s, which is Mach 1929.
I believe that everyone here is assuming that the speed is being scaled to the planet size, when that is not the case. It is being scaled from the visible atmosphere distance between a direct view scaling's sight and Alabasta.