If you were wearing glasses to counter astigmatism why would you want to remove them ? Surely it would make things worse.
Removing glasses (short sightedness) when taking short distance shots will improve your view of that target. That is in my view taking advantage that other shooters can't take and therefore is cheating.
Not all none glasses wearing shooters have 20/20 vision but have to set up their scope to suit their eyes.
Why would wearers of glasses want to remove them for closer shots unless it gave them an advantage.