Right now, already existing subdomains or DB names are locked as declineable-only, not approvable. This is because when it was being designed onhold didn't exist and you could only approve or decline. But on hold needs to be available so they can choose another name. You should every option but approve.
Since this is technically a feature request, lowering to low, but hopefully I can get to this within a week.
@Universal_Omega This is not low priority. There are currently two requests that this affects.
Also it's not really a feature request since it's unintentional. It used to let you do anything even accept but accepting would give a creation error.
It is intentional, before the on hold status, so changing it is behavior has CW is defined to force declined, it does not check for anything else, regardless features are technically low priority, but in this case, it does not mean I will push it out, I intend to work on getting this changed within a couple of days anyway.
I guess this is kind of an edge-case between bug and feature but since it is changing behavior, I considered it a feature request.