Geoprivacy/ Obscured Taxa on Projects

On a project how can the host apply geoprivacy to a taxon, and/or how to get iNaturalist to consider a taxon as poachable/in need of obscuring.

Add a flag to the taxon in interest.

Geoprivacy is determined per observation and is applied either because the taxon is automatically obscured as endangered, or because the observer chose to obscure that particular observation.
As Melodi said, you can flag a taxon if you think it needs auto-obscuring.