I get the sense that the army is something he didn't ask for. Like perhaps its an act of solidarity for his actions in Man of Steel, soldiers who stand with him even though he doesn't want it.
Also, I feel that Bruce Wayne is both afraid and jealous of Superman. Batman has likely gone through a lot of shit and lost a lot of people close to him, and yet he continues to be a branded a menace. Meanwhile Superman swoops in and is a seen as a god to many. The Alfred quote says as much with the line “That’s how it starts—the fever, the rage, the feeling of powerlessness that turns good men… cruel.”
Also, I may be opening a can of worms here, but I cannot stand the argument lodged against superhero movies where people say "X would never do Y". I get that there are rules set in superhero universes and yes there are things that some heroes would never do, but I don't see what is wrong with occasionally breaking these rules. Like, "Superman would never kill". Well... what if he did? How did he make the decision to never kill? I find these sorts of things to be interesting territory to explore, especially after 5+ Superman movies and 75 years.