Are you sure that explosion is constant for every frame it's active, and not a rehit?
The claim is coming from myself, a Palutena main, and I also know about something as simple as snapping the ledge from above. That makes the ledge snap itself invincible, but that doesn't necessarily mean it makes the rest of the warp invincible.
I've been hit mid-flight many times, whether it be someone charging a smash on stage (when I try to warp past them), or for example falcons throwing dairs and bairs off stage mid-flight. That is, I disappear visually, but am still hit before my destination (the ledge, and I am not hit right where you grab the ledge either, nor the point where you initiate the warp, but *between*, where the opponent's hitbox is placed). If you check KuroganeHammer, it even lists Warp as "invisible", not "invincible" (let alone "intangible"), while characters like Mewtwo and Zelda have "intagibility" frames instead, and I never experienced being hit mid-flight with theirs.
I'd like you to explain how I'm still getting hit if it is invincibility, or why the data says it's invisibility only. Whether you snap the ledge from above or not to get rid of the 2 frame vulnerability when snapping the ledge doesn't matter when I'm not being hit at the ledge, unless if Warp has similar properties to Quick Attack, which would be most surprising.