People have reasons that's why they will change their username and it could be privacy related or just for fun.
Whatever the reason, I guess if the username change is not announced publicly by the user or admin himself we should not be bringing it to the public.
Igebotz and The Sceptical Chymist have discussed it publicly but others are new to me.
Here is a take from theymos on discussing username changes
Why are you guys posting the old names of people who clearly needed their names changed for privacy reasons? Obviously any data posted online is going to be quickly archived somewhere, but that doesn't mean that your highlighting/reposting of it has no effect. In some cases you may literally be putting lives in danger. If you were investigating a scam or something, that'd be different, but you seem to just be indiscriminately & recklessly dredging up data that would best be forgotten.
I guess you need to revisit your list and ask the users for their consent to be on this list.
Edit:Some names are not included, by request.
I think I overlooked your notes, looks like you already did the exercise if so then well done.