Advent looks like something cobbled together at minimal cost.
Phobos is just ill-advised. Was some of that really images and sounds of alien creatures ie 'xenomorphs'?
But, these short films exist in the canon. So.... David's transmissions, made some time after the events of Alien:Covenant, must have travelled through a timewarp to reach W-Y before the mission launched, enabling W-Y to plan out the whole thing. Oh, you don't like the thought of something burrowing into your body? Great, you're perfect for this mission! ....and by the way that means David is really Walter too!