I suspect that Chiaki filled a similar position in Akiko's eyes as Midori does now... Not in actual job, but as a most highly valued associate. I wouldn't advise Chiaki to publicly embarrass Akiko, but then that's not Chiaki's style. Still, I imagine behind closed doors Akiko allows certain people to speak freely. But I am sure that's how she looks at it... that she allows it, even if she doesn't make pains to make that clear.

As I've written her since her first appearance (where she was a bit broader than she later became), she has two main traits by which she operates: Her reluctance to dispose of resources that may one day prove valuable, and a lighter touch in manipulating those resources into getting the most out of them.

Whereas the Lynchpin might simply lean on everyone to intimidate them into doing what he wants, Akiko is more likely to find the right shaped peg for each hole she needs filled... one that won't need a great deal of force to fall into place. She understands how far she can push Chiaki, or the Legion, and understands when she's putting energy in against diminishing returns and cutting off a future resource in an exercise of ego. And she takes different tactics with different personalities. With Visionary she tends to stay pleasant with an undercurrent of menace. With Rupert, they apparently both know the score, and so she is perhaps more blunt with him than with most anyone else.

One final thing to note is that Rupert was right... this wasn't about a little girl. Akiko is flexing her muscles for show in this story more often than she normally does, first with the corporate executive and then with the gang. It, like everything else, is a very calculated move in her eyes.