If this rumor about the high return of DF'd ones is true...
100% sure it's not. 300 DFed people returning to a convention. No way. 300 DFed people would be 3 or 4 per congregation attending. Not. A. Chance.
This is at best 300 (and it might not even be that high) people who didn't bring badges for one reason or another getting told to report to the attendants office and get one. The majority of them would have been dubs who didn't get one, unbelieving mates, studies, inactive ones and so on. Some would have been Dfed for sure but a small minority.