You misunderstood (or i wasnt clear in how I conveyed what was in the study).. the 90% figure is from the study itself and represents the portion of the numbers stated (64K) that were in states where they couldnt get abortions. 10% of the 64K number were already known to be in states where getting an abortion for them would have been legal.
So we already know that at a minimum 90%, but in reality some portion of them can go out of state. I have no idea what that is, but whatever it is we know these numbers are just made up esitmates and the real number is quite a bit smaller than this, at least 10% smaller for sure, but in reality probably much much smaller.
The main point is, this number does not remotely represent the real number. It was a low-effort estimate made, as the study itself states.