Simon
As I've said above, a flag is not "displaying people's information". It is a trait that someone has that is shared by millions of others and in no way identifies them.
As JWs form a small part of the population whilst it may be true that there will be millions of people who share a certain nationality it won't ever be true that millions of JWs share that trait of a single nationality. I just looked at the 2012 YB on jw.org and for example there are 7 witnesses in Norfolk Island.
It is good practice in surveys for example to anonymise (the spelling of that probably gave my own country away) the results by grouping where the numbers are very small in order to protect people.
The pain caused to many by being disfellowshipped is immense and in the rare circumstance that a person's nationality gives them away it may cause irreparable damage to their families and relationships.