Retention issues don't affect OCS selection numbers, you can shove a newly qualified LTjg into a spot where they need a LCDR and call it good.
They need to commission a specific number of each designator per year to maintain proper numbers per YG, doesn't matter if they are getting trained on their designator or watching Judge Judy, they are still commissioned in that YG.
This isn't the first time they have had SNA's/SNFO's or other designators just sitting around and yet they kept commissioning to maintain the YG numbers. We were seeing some stash ensigns so frequently it was like they were permanently assigned lol.