Felipe Ortega, 13/02/2014 14:57:
My question is: are there any reasons for redacting this (apparently public) info? I can't figure out why this could be sensitive data.
It's not redacted, it simply never existed. There aren't even log entries for old registrations; on some wiki(s) the field was populated with guesstimates. See also https://bugzilla.wikimedia.org/show_bug.cgi?id=18638 , https://bugzilla.wikimedia.org/show_bug.cgi?id=22097 depends on it/is a duplicate.
Nemo