Mirror!Steve would so think he was doing what he does for the 'greater good'. He knows what's best for everyone. He keeps his friends 'safe', even if it is against their will often, and doesn't understand why some of them have turned against him. Can't they see that his way is the right way?

And well the government was faulty so of course he had to take over, for the greater good not because he wants to rule...

And isn't Tony better off? No more worries about his heart, or his company. Steve can keep him from making stupid rash decisions. He doesn't have to worry about letting people down and he certainly doesn't have to risk his life anymore. Why doesn't Tony see that? Why does Tony resit so? Steve only does this because he loves Tony after all, and he protects what's his. He wouldn't have to keep Tony restrained if he would stop trying to run away...