People stated that this is a bug, so I withdraw the question. Crap, I hate unfinished accolades...
My fleet did this mission yesterday during an accolade-hunting expedition to Defera. The dialogue to drop the force field appeared normally when we walked up to it.
There isn't a console or other highlighted objective... just kill the borg, then walk up to the force field. You should receive a prompt to signal the engineer. Your officer will play the 'wave' emote, then the engineer will drop the force field.
There should be a forcefield in that room, after killing the borg u would walk up to the forcefield, interacti with the trapped deferi.
That deferi then would walk over to a console to drop the forcefield, after which u go to him to intract and get him to follow u, while some more borg spawn after interacting with the deferi.
Trying to walk towards the deferi before the interact would result in a repulse.