I think if these questions are more than academic--i.e. you are seeking to take some kind of action or make a recommendation, I urge you to seek experienced legal counsel and not rely on the opinions posted here.
Your initial post stated that the developer owns no property in the neighborhood. Now you are asking about a situation in which the developer owns the common areas.
As I read the quoted section you provided, as long as there are uncompleted homes without a certificate of occupancy then the declarant may retain control. Whether or not that would stand up in court is a different matter, entirely.
I would guess that somewhere in the governing documents there is a statement to the effect that the declarant may transfer rights to development and control of the homeowners association to a successor. An example might be:
"Declarant" shall mean the developer and any successors and assigns of Declarant who it designates in one or more written recorded instruments to have the rights of Declarant hereunder, including, but not limited to, any mortgagee acquiring title to any portion of the Property pursuant to the exercise of rights under, or foreclosure of (or by acceptance of a deed in lieu of foreclosure of), a mortgage executed by Declarant; provided, however, that any such mortgagee so acquiring title by virtue of foreclosure against (or acceptance of a deed in lieu of foreclosure from) the Declarant shall not be deemed to have assumed any prior obligations or liabilities of the Declarant hereunder.
If there is such language in the covenant document, the mortgagee then assumes the rights of control over the homeowners association, and has the right to transfer such control to another builder/developer.