Mastermind is the tag given by Sree and BB. It just means someone who strategises or plans successfully. It does not mean someone who controls or likes to control. Somewhere Sree likes to control those he supports for eg KV, Dipika, Shiv.
Romil never controls and should not control, anyone who tries to do that is going to fail badly. Nobody likes to be controlled. The actions which come out of free will are best. Romil is not their elder brother or father or anyone else to control or correct unless he is asked for. If the situation is critical he does that. He did tell Surbhi to stop her non stop screaming but she did not listen. He tells it calmly and if the member is not willing then he leaves it. He did stop Dipak regarding Jasleen matter.
Yes BB does manipulate the behavior by conditions in task.