No, I think you're completely misunderstanding this. It was not the director, it was the writer, and he was talking about this as an upcoming project he was working on, without even specifying that it was an anime. This was not a promotional interview where he said "this show is like Watchmen yo!" but a general interview about writing and superhero settings (this was a tokusatsu magazine, targeting readers who are interested in stuff like Ultraman, Kamen Rider, and [Whatever] Rangers shows).
Like I said, the inspiration is about the setting, not the characters. The heroes were mentioned as being distinctly Japanese type heroes. The important point here is the premise of "how would a modern society deal with superheroes showing up over a period of time and becoming a management problem for authorities", and also the "alternate history" hook. Those are the inspirations from Watchmen.
As far as being political and edgy, I think you can fully expect that. Mizushima and Aikawa has never done anything together which isn't political and edgy, and even on their own with different directors/writers, they bring that sensibility with them. Mind you, the quality is not necessarily good, but the intent is there.
Mizushima and Aikawa working together brought us the "amazing" nazis in the original FMA, and the quirky but muddled social commentary on the Japanese political system by transplanting Meiji-era detective stories into a futuristic setting in Un-Go. Mizushima also tackled a lot of current socio-political issues (badly) in Gundam 00, while Aikawa did the same (with even worse results!) in Eureka Seven AO. So I'll be really surprised if there isn't a heavy handed element of commentary and edginess in this show as well.
