Some people seem to not get how the internet works. Regardless of using a pseudonym on one site, if you have publically available info elsewhere on the internet (and most people do in one way or another) then posting real information about yourself on said forum can easily lead to your other information available on the net.
If anything this should just be a lesson to people to have proper internet security and to keep personas separate regardless of what name you are using on different sites if you don't want them linked together.
On the other hand I also agree that people shouldn't out each other and share personal details if others don't want you to.
It's half a dozen of one, six of the other.