Just did this ending and it still doesn't make sense why we need a very strict set of dialogue choices in a single quest to trigger it. I did something very similar in my 1st playthrough, missing maybe one or two of the "correct" dialogue options. Johnny reacted pretty much the same, but, well, didn't trigger.
It's specially frustrating because that's the only actual ending where V takes matters into his own hands and it fits quite well with the rest of the story from where I was sitting, but even if it feels Johnny acknowledges V, we can't get that ending because of a single moment in a single quest. Rewinding to that point and choosing different options don't add any replay value if you went in a similar direction with your choices, but it makes me (and probably many others) lose hours of quest progress, new gear and skill upgrades.
It's specially frustrating because that's the only actual ending where V takes matters into his own hands and it fits quite well with the rest of the story from where I was sitting, but even if it feels Johnny acknowledges V, we can't get that ending because of a single moment in a single quest. Rewinding to that point and choosing different options don't add any replay value if you went in a similar direction with your choices, but it makes me (and probably many others) lose hours of quest progress, new gear and skill upgrades.