Story-wise, Moka's plan is absolutely crazy and I'm shocked she felt the need to go that far to save the relationship. When Moka originally mentioned to the trio that she wanted to surpass them, the most I expected was the trio giving Moka some advice based on their sexual experience with Ueno.
From their advice + further research, the next time Ueno and Moka have sex, Moka will try to act more aggressively. Ueno would probably hesitate seeing Moka acting more aggressive since he was the one who wanted to take the lead in development and probably thinks Moka acting like a dom would be out of character. However, after remembering Hina's advice about sex(let women take the lead), he relents, and both eventually enjoy the new dynamic in the relationship.
Instead, Moka wants the bully trio to be active participants in the development plan and they all signed up for it. Even after the trio promised to leave Ueno alone or act platonic towards him. After seeing the tone of each trio's last focus chapters, you would think this plan would never materialize, especially from Moka's mind. I guess the trio felt like they owe Moka a huge favor for leaving her to deal with this predicament...
Of course, if I was Ueno, I wouldn't feel O.K that my girlfriend felt the need to do this behind my back. He thought everyone moved on from this and he seemed content about his current situation with the trio. Yet here he is masturbating in front of them with his ringleader girlfriend present to watch all of this.
Yup, I would have permanent trust issues after this incident but at least I'll get to do a 5p which is a nice consolation prize, I guess lol.