Aoi is pretty, what more reason does a random guy need to woo a girl?
And Oga knows how tough Kunieda is. He's not about to butt in on something that he 'knows' she can take care of easily.
If she was drawing away and was not blushing, there would have been a higher chance of Oga stepping in on that. 2x if it was Aoi KUNIE... Anyway, she should know better than to rely on Oga for something like that on the fly.
And I can hear more cries of how 'weak' Aoi has become from her 'Queen' persona...