Oh No! Cows, you do realise if those players who did manage to get into the top 100 after the original deadline expired don't receive their medal your going to have quiet a few complaints and rightly so. It's not their fault they continued to hunt after original expiry to enter the top 100 Ladder, there is no rule saying they could not do so, only players opinion to this effect. I think it would be prudent to allow those who were on the Ladder at original expiry time to receive their medals along with those that have gained access after the original deadline.
Maybe for future Global Events, which you intend to extend, you can make an announcement on the homepage and send personal messages stating that you are going to extend an event but entry to the top 100 expired with the original deadline. This might prevent this " who's in the top 100 " from happening again.
Cheers.
wil72