When Kindle for Mac/PC updates in-place, it must keep the same user key (otherwise all the books would need to be downloaded again). So it's possible that someone installs Kindle for Mac pre-1.25, gets the key, and it then updates to 1.25 and with the work-around, can still get access to KF8 files for which they have the key.
But this, I admit, is pure speculation. And probably about as far as we're allowed to go on MobileRead.
