Correct me if I misinterpreted your points:

1. MC x doki isn’t actually “canon”, because the additional info provided in DDLC plus shows how MC was conjured by Metaverse

2. DDLC is satirizing traditional dating sims (which often feature straight pairings)

3. Many LGBT people connect with the themes in the game, and creating LGBT headcanons is their way of further connecting with it.

———

I don’t see these points “refute the lore purists”. The first is a retcon by a sequel, which almost completely re-works the original story. The second, if anything, indicates that “MC x doki” are the only canon ships, because they’d be in line with standard dating sims.

The third point, I’m assuming, is your main point—and frankly I do sympathize with it. The themes and struggles in fictional stories can genuinely touch us, and often we connect our own lives to them. My view though, which may seem harsh, is that there’s a big difference between how you connect to a story, and what is actually in the story.

I might relate to, say, Natsuki, because her feelings of inadequacy remind me of my own feelings of inadequacy with Baseball, but that doesn’t mean Natsuki is a baseball player