Here’s what I’m thinking in terms of the future dialogue of TR-8R:

Password: fanedit

The janitor bit helps tie in to the subsequent scenes where Finn’s knowledge of the Starkiller becomes important. I wanted to include some dialogue about the Starkiller itself, but I doubt that the Stormtroopers would have divulged any of that info on the battlefield and it was also too awkward to fit into the fight.

Additionally, Finn’s status as a janitor becomes much more of a pejorative and distinction from the other ‘real’ Stormtroopers, which goes a long way towards justifying his willingness to wantonly kill them as he escapes the Finalizer.

Finally, the line about Ren choosing Finn over the judgement of Phasma increases the competence of the rank-and-file members of the First Order since Finn’s defection is no longer on their hands, and it opens up a lot of interesting speculation with regards to the Finn/Kylo dynamic which is one of the most underbaked interactions in the ST.

Why did Ren choose Finn? Maybe the Force guided Ren to make this decision on the eve of their Jakku assault, feeling that Finn would be important in some way. This would be ironic and correct, and even makes sense if Kylo was being unduly influenced by the light side and its mysterious ways. Kylo’s dramatic look at Finn after the villager massacre and his immediate knowledge of Finn’s number heavily implies that Finn is notable to Kylo beyond his status as a stormtrooper, after all. Finally, Kylo’s scream of betrayal at Finn in the Forest has much more significance if Kylo was the one to personally pick Finn for his assignment.