Why does talking to Pacer locks you out of the diplomatic option

This is a follow up from my previous post on the mission G.I. Blues https://www.reddit.com/r/fnv/s/guPZCJUgP3 Apparently talking to Pacer causes the quest to automatically lock you out of the peaceful option of the mission And yes I’d: -Spoken to Julie -Mentioned Julie when talking to Elizabeth -Talk to The King about the supply drop -HOLSTERED my weapon & wore a merc outfit Is this common within the game or is it some quest that locks you out of another option because you engage in a dialogue with someone