Ok. Now could you point to the part of your argument that explains how every character in the game with the exception of Samus (since it's only usable on Samus) can go from being off in the magnifying glass when it is released at near/max distance to suddenly being close enough to the edge in the 15-20 or so frames of lag Din's has after the explosion's hitbox would be hitting to somehow disrupt your edgehog and edgeguarding as usual like if you had instead sat there and waited?
Fox: You can just edgehog if he's that far out. If he's closer, he can just illusion, and you'll probably miss Din's Fire.
Falco: Same thing, but he can be even closer to the stage for an edgehog to work.
Marth: You can hit him, but his recovery is so predictable, why not just hit with a stronger move? Similarly, if he's far enough away to be hit by it, you can probably just edgehog. If he's closer, just stay on the edge, use the Up-B stall for invincibility frames, and if he lands on the stage, ledge hop a fair.
Sheik: Her recovery is such that if she's far out enough there won't be a point in doing anything but edge-hogging. If she's close enough, her invincibility frames from her up-B will prevent Din's Fire from harming her. Instead, you should just edge-hog, then ledge hop a fair if she doesn't try to sweet-spot the edge.
Peach: Might work, but her recovery is too good for Din's Fire to have any real effect. Peach can just double-jump into a float or fast fall into a float or up-B. Still better to wait for opportunities to hit her with bair.
Captain Falcon: Why would you even try it? Zelda's crappy dair kills better than Din's Fire here. Just stay on the ledge. He can't sweet spot, meaning he'll either be edge-hogged or he'll land on the stage, which sets up for ledge-hopped fair.
Ice Climbers: Not enough time to use Din's Fire if they use up-B to recover. If they use forward B, you can just space a fair or bair. Or ledge-hop one if it looks like they'll land really close to the edge.
Dr. Mario: If he's that far out, he's dead already. Just edge-hog. If he's closer, just bair or fair him, or edge-hog and ledge-hop a fair.
Jigglypuff: Not sure about this one. Jigglypuff can just rising pound to get away from it.
Mario: Might work, but his recovery isn't great. You can just wait for him to get close and fair him. His up-B sucks.
Ganondorf: While doable, I don't see why you don't just sweet spot fair or bair. He can't sweet-spot the edge. You just ledge-hop fair if he tries to go above it, and if he tries to sweet-spot it, put the controller down and laugh in his face.
Link: Fine, it might work against Link. I'd still prefer invincibility frames from ledge-stalling and then being able to bair through his up-B, though. But Din's Fire can set up Link nicely for a fair in this match-up. While he is recovering, that is.
Luigi: I don't think there's much of a point in trying. If he misfires your bair still out-prioritizes it, so you can just use that. If he's coming from below, you can just do the stall and edge-hog or just ledge-hop fair if he tries going onto the stage.
Donkey Kong: Dair can kill him. It's pitiful. Hitting him with fair is difficult, though, because of the ridiculous range of his up-B move. Din's Fire might work here.
Roy: It's like Marth's recovery but worse. Why bother?
Young Link: His up-B lacks the range of Link's, so it's much easier to punish with bair. Still, I can see it being used here. I'd still prefer fair or bair to it.
Pikachu: Good luck with that.
Yoshi: The fact that he takes 0 knockback in his double-jump effectively negates the usefulness of Din's Fire.
Zelda: Uhh, good luck hitting her with it. She gets invincibility frames when she presses up-B, and she goes ridiculously far. You should just hang on the edge and wait for her to land, then hit her with fair.
Mr. Game and Watch: Usually recovers from too low to be able to hit with Din's Fire.
Ness: Din's Fire works on Ness, but it's difficult to time (as he may up-B into himself before Din's Fire reaches him), and if your move whiffs, you might get hit. It's best to hang on the edge and ledge-hop a fair where he lands.
Bowser: Lawl, do whatever you want to Bowser. Just don't tell Gimpyfish or he'll challenge me to a money match. >_>
Kirby: It's doable.
Pichu: Good luck with this one.
Mewtwo: Doubt it. Mewtwo is very difficult to edge-guard in general. Hitting him with Din's Fire is just ridiculously difficult. You just rely on his light weight to kill him off the side. But, due to his lightweight, if you fair or bair him at around 50%, he'll be forced to land his up-B close to the edge. And that means...
In general, the problem is that if a character is far enough away to be placed into a proper Din's Fire -> Fair/Bair set up, you can probably just edge hog. If they're closer, her fair and bair are faster and more effective for edgeguarding, less likely to whiff, less likely to get her punished for whiffing, and much easier to do.