I appreciate all you say, but I think there is another way of looking at it. In a very real sense, Cicero's political life ends when he sends the letter; it is his last move and like so many of his moves it is too little too late and entirely futile. He has done his duty as a citizen, and it was not enough.

What remains is how he comports himself in terms of his duty to himself as a human being. He is a philosopher and a Stoic at that; he needs to carry himself with grace, fulfil his duty to his slave and die with dignity. Pullo allows him this, killing him with an efficient stroke, allowing him to settle his affairs and his mind, treating him with respect over the peaches. For me, the scene works because they both act with dignity - imagine how different it would have been had Octavian and Antony sent one of the criminal gangs from the Suburra to chop him to bits.

Cicero appreciates that he has been allowed a 'name' killer; Pullo says 'less stuck up than you'd think'. Both behave as well as is possible in the circumstances, which are horrid - it is one of the points where we are reminded that these people are aliens, but that sometimes aliens have more grace than we might manage.