True, but its not the first and only anime I've watched in Adult Swim that seems to reflect a negative view on the US, at least on the US government and military. Like in Blood+, US bases in Okinawa are being used to conduct inhuman genetic experiments which ended up making a meal of the local population. It all seems to be a trend going around.
I think that a lot of Japanese do indeed resent or have mixed attitudes towards the US presence in their country. But I would just like to point out that an out of control military, military experiments gone wrong, a military that is interested in provoking conflict etc. are prevalent themes in American pop culture and movies as well. So I don't know if that illustrates a real sustainable base of opinion for political real-world action, I think it just shows that writers everywhere realize that involving the US government and military makes for a good conspiracy theory story.