Firstly, Gunn is a comic book nerd and a screenwriter and all he's tried to do is marry a lot of things together, which is why it took him a long time to find an angle to come in from, repeating what I said earlier.
And secondly, I really understand the tokenism directors offer in film because the majority is written from the Caucasian eye's view of ethnic interaction. So, imagine trying to import that view from the comics interpreting Black interaction from the page to the screen. It's like a double Caucasian eye in that regard. I wasn't sure why 'Mr Terrific' needed any slight ebonic type and bombastic language to rep a Black man (a superintelligent one, at that) on screen. It was a little jarring to be fair, but thought this may have been a way for Gunn to 'ground' and relate the character, somewhat. Whilst I think he should have discussed the overt depiction with others whom the character supposed to represent, in the end, I found it minor compared to the overall effectiveness of the character on screen.
'Superman' putting himself in peri;? Sure, otherwise what's the point in making the film? There has to 'stakes' involved or the film would have lasted 10 mins, tops!
As for the 'alien surrendering himself to authorities', is this not a spin on what Snyder did? Both tried to present 'Superman' indicating himself as not a threat despite the fact he could smash everyone in milliseconds! And he does to the US as he lives there, no? He chooses to live in a place where he interacts or he could have just lived in the Antarctic away from Humanity.
ironically, Gunn addresses US jingoism to the audience and, somehow, you looked past it!!
But also, I agree, it could be a film made for 12 year olds that grown ups should ignore...