Without knowing any specifics about this user, I think I can answer to some extent.
You’re linking to User:Beldin on the wiki. Is that the same as the ‘beldin’ user account on OpenStreetMap? You might think it’s safe to assume yes, but unfortunately these are separate accounts with no tight binding, and no guarantee that these are the same person. Certainly an automated process can’t take wiki user page labels into account. beldin (the OpenStreetMap user) is one of only a few hundred users who decided to decline the contributor terms, so I guess his contributions will have quite simply been redacted through the normal process.
On the wiki, user beldin seems to declare his contributions PD, meaning he/she doesn’t care what license their data is re-distributed under. To my mind it is nonesense to do that and then also decline the ODbL license change, but I’m sure this user had their reasons. In fact some other declining users have done this, but arranged to have another user “adopt” their contributions. Guess nobody made such arrangements in this case. beldin may not have wished it. I’m not sure of the legalities in that case. If their declaration of a public domain release is taken literally, then they forgo any choice in the matter. Any other user can adopt their data.
But anyway… You (Chris) refer to a new gap in Adelaide. Where exactly do you mean? How is the remapping effort progressing there?