The irony portrayed here by brutus is perceived in the way he wants the conspirators to kill Julius Caesar "kindly" it means, with respect and dignity. That is not logical for the kind of murder he is proposing is certainly not kind nor respectful.
In the soliloquy in Act 2 Scene 1 in the tragedy of Julius Caesar explains Brutus' involvement in the assassination plot against Caesar as he thinks about the consequences if Caesar is crowned. He compares the crowning procedure of Caesar to that of the hatching of a serpent from the egg. He assumes that when Caesar would become the king of Rome he will show his cruel nature and bring destruction to the people of Rome. Hence, Brutus joins the conspiracy against Caesar in order to prevent Rome from the ambitious nature of Caesar in the coming future. While addressing the crowd after the murder of Caesar, Brutus says that he has killed Caesar because of his growing ambition which would be very harmful to the citizens of Rome. He adds that he would never accept that because of one person the whole of the Roman empire would be trapped in the web of slavery.
