That's all true. I'm not really arguing against the tribunal scene anyway (although it would have been nice for them to have shown something of substance being said by either the minister or M herself), but more arguing that the supposed "code" that has been ascribed to Silva in this thread is at best flimsy and, more likely, something that's not really meant to be read into the character.
Hmm..., not sure about the code.
Well, on the face of it Silva is the villain of SKYFALL, he has to behave in villainous ways. And probably 80 per cent of the audience will clearly identify Silva as a vile and murderous terrorist. So far nothing new, all typical action thriller lore.
One layer deeper Silva is a - former - colleague, perhaps even a former version of Bond (who's to say the 90s 00-section didn't employ a binary division? the real-life counterparts of 20xx+ sure as hell do.). It's said he was working beyond his assignment and briefing in order to half-heartedly justify M's handling of his case. Fine, the bloody foreigner - strange accent for a SIS agent - had it coming. Only, Bond is regularly acting beyond his assignment and briefing. Lucky he didn't end up in Chinese custody. What distinguishes Bond (good) from Silva (bad)? Less than we'd like to acknowledge perhaps.
And yet another level deeper we learn that the - unpopular among many fans - mother figure M deliberately, intentionally uses her mother status with her agents, and consequently recruits the best of them amongst orphans. As she did with Bond. As she no doubt did with Silva. Who, it has to be said, is not able to harm his 'mommy' himself until the very end, despite various occasions. And this in light of the fact he was willing to die for her and was aware - she confirmed it herself - that she was the one who sold him to the Chinese service.
By this reading we must reconsider the role of the villain in this Bond film. Because it means M didn't just trade in a blunt object - or in Silva's case perhaps a highly honed specialist tool - but a surrogate 'son'. Or at any rate somebody who considered her in a very real sense as a mother of sorts. Which puts the entire affair on a most unexpected level for a 'mere' Bond film.
But this reading - always assumed it's legit in the sense of being intended by writers and director - is indeed only possible if we get the chance to review the character of Silva and his actions inside the plot of SKYFALL. Had Silva been depicted as the utter monster we are by now used to in entertainment terrorist country we wouldn't give the guy one second thought. Many people don't as is. So in a way I suppose there were limits to the horrific and dangerous potential of Silva. There had to be a 'code of conduct' for this villain; perhaps not meant as a definite set of rules, but surely as a means of focus for his actions.