The OG doesn't so much as hint at this version of events. It's a DoC retcon. They've forced Lucrecia into a series of psychological 108 degree turns simply in order to exonerate her, and they don't even manage to achieve that. If that's the canon now, then I can only throw up my hands in despair.
DoC isn't a retcon of the OG. Mainly because the OG is so broad when it comes to the events with Lucrecia that DoC could do almost anything it wanted and still be canon. Many of those scenes don't even have dialouge! Adding in new information the audience didn't have about certain events doesn't a retcon make unless it actually directly rewrites what happened. Which isn't what DoC does with Lucrecia.
The main things that are deliberately spelled out in the OG is how Lucrecia feels at the end of the Jenova Project, how Hojo felt about her in general and how Vincent saw the Jenova Project. Which essentially are...
1) Hojo views Lucrecia as an object to get what he wants out of the project
2) Lucreica is asking after Sephiroth and Vincent while Vincent is asking after Lucrecia and Sephiroth
3) Lucreica regrets what happened with Sephiroth
4) Lucrecia dreams of Sephiroth
3) Lucrecia tried killing herself, but the Jenova Cells in her won't let her die
4) Lucrecia is very comfortable talking with Vincent and vice-versa
5) Lucrecia has Vincent's Limit Break manual and Ultimate Weapon with her
6) Vincent wants Lucrecia to be happy doing whatever she wants to do
7) Vincent didn't want the Jenova Project to continue as it involved human experimentation
8) Hojo says he and Lucrecia both want this
9) Sephiroth really is Lucrecia and Hojo's son
10) Vincent thinks his monster transformations are his punishment for not stopping the experiment
All this stuff is based on what characters come out and actually say. So... whatever canon DoC comes up with has to fit with this.
The secondary stuff is what is shown as scenes in the OG, but without any dialogue. This is stuff involving a lot of character interaction before things went south as well as Vincent falling into Hojo's clutches. These are a lot more open to interpretation because of the lack of dialogue.
1) Vincent and the scientists come to Shinra manor
2) Vincent and Lucrecia are with each other as they walk around Nibelheim
3) Vincent and Lucrecia are holding hands and then she drops his hand and runs away from him
4) Lucrecia is hugging Hojo while Vincent watches. Vincent turns away and leaves (this is when we get Vincent's "if she's happy, it's okay" thought)
5) Lucrecia is pregnant with Sephiroth
6) Vincent, Lucrecia and Hojo are discussing the project (one of the *very* few scenes with actual dialogue)
7) Lucrecia collapses while pregnant
8) Vincent and Hojo get into an argument, Hojo shoots Vincent
9) Hojo experiments with Vincent at the Shinra Manor
10) Vincent gets up from the table and realizes he's been experimented on (this is when we get Vincent's "this is my punishment" thought)
This stuff is... a lot more nebulous and a lot more prone to spawning headcanon because we don't know the *actual* context for what is going on in most of these scenes. So we can kinda do with them what we want to. DoC would basically be doing the same thing too if it didn't want to retcon them.
And... that is what DoC is doing with Lucrecia. It is adding in dialogue to these scenes. It doesn't say these scenes don't happen anymore. Or even necessarily happened in a different way. It just adds in dialogue and gives the scenes more context. That new context is... not really retconing anything, it's just making a more detailed picture of what was very broad strokes in the OG.
But clarifying a story with new information doesn't make a retcon. All serial story-telling works that way. The Audience often starts out with a broad, general idea of something that happened in the past and then later gets new information that clarifies what really happened. And as long as that new information doesn't completely overhaul the general idea of what happened, then that isn't a retcon. It's like someone saying they were a doctor in the past when you first meet them and then later revealing they were actually a black-market surgeon who operated out of their garage.
The other thing is... the writers of DoC are the writers of pretty much all of Vincent's scenes. Chiba was the guy who made the vast majority of Vincent's cutscenes/dialogue in the OG and managed to get them all into the OG in the first place. That's *why* he was the writer for DoC. Vincent's story was largely something he and Nojima came up with and DoC is just him fleshing it out without the confines of the PS1 hardware.
It's just... a very consistent theme that the ideas of FFVII were a lot more developed in their creator's minds than they could make the PS1 pull off... and the Compilation is their chance to pull the FFVII they always envisioned off with way better hardware.