When Bernard asks Ford if he has hurt anyone else, Ford says “no, of course not.” Now if Ford asked Bernard to ‘take care of’ Elsie, then why would he say this? He’s stated in no uncertain terms that he considers hosts simply machines. He scolded a tech for covering up a host at one point. So, why lie to Bernard. Bernard, at least at this moment, already knows he killed Theresa.
One explanation is that Ford considers Bernard ‘special’ (whatever that might mean). This could support the Bernard is the likeness of Arnold theory.
Another, rather radical, explanation is that Ford doesn’t know that Bernard ‘took care’ of Elsie. This would open up another can of worms.