Well if you guys look at the launcher for the game he returns in chapter 10 and has two missions one to convince him to join the other you play as him probably intended to explain how he survived the death blast. I loved having hk 55 as well as hk 51 they both have their uses now the question is how will hk 55 react to hk 47 in the false emperor flashpoint.

as the title says it'd be nice to have two companions fighting along side you while questing like back in the ktor's

or they could put it on doc to further joke that he is doc holiday from tombstone