I went back and re-read the solicitation to clarify what you might've meant. Honestly, it just made me more excited for Morrison's take on Superman. According to the solicitation, the world distrusts him because he's the first superhero. Knowing that Morrison basically considers Superman to rightfully be the greatest superhero of all time, I'm excited because we'll get the opportunity to see him craft the story of why the DC universe, unlike the Marvel universe, implicitly trusts its superheroes for the most part.
Imagine if a superpowered demigod showed up one day out of the blue. Wouldn't you be utterly f***ing terrified? I sure would. Now imagine that that superpowered demigod turns out to be the awe-inspiring, warm, universally good paragon of humanity that Morrison's Superman has historically been. This is a world that was confronted with one of the most frightening doomsday scenarios ever conceived--a being so far beyond humanity in terms of power that he's 100% unstoppable and can do literally whatever he wants with impunity--only to find out that this apocalyptically powerful being turns out to be possibly the most decent, honest, and morally righteous person they could imagine as well. That's about the only thing that could possibly shape a whole world to accept and put its faith in superheroes as a whole. Because Superman was the first, the universal embrace of superheroes in the DC world actually makes sense rather than being something you'd have to extend your suspension of disbelief to cover.
Granted, if it were someone other than Morrison, I'd be worried about their potentially botching it. But Morrison's basically already given us a perfect Superman in All-Star Superman, so I have no doubt that he'll give us something at least approaching that level of quality in Action Comics. The "first superhero" scenario is as good a ground as any to start that on.