Note: I don't say that I'm right, or that you are wrong, but you forgot some points in your reasoning.
The Don just killed one of his own in front of his "soldiers" and family, for taking Mina's side,
Something that only half a dozen soldato and two/three capos, plus the daughters and Mina, know about. Nazazi said it, "the circumstances of Brizio's death cannot leave this room". A handful members of the Family know why Nazazi killed him, all the others don't even know that it's Nazazi who killed him.
and sent his daughter to deliver the course as a apology to the Deluca family,
For the contract, what is different ; as Siobhan could say, it's a question of principles, but I guess that for Nazazi it's more a question of rules.
If you have something against a top member, and even more a core member, you solve the issue by yourself, you don't use a proxy. The Ombra should have terminated the contract the instant they discovered that the target was living in the main house. Imagine the consequences if it was otherwise...
Assassins are tolerated because they are more useful than they are a threat, what is possible only because there's people that are said to be out of reach. Your child can go to school, without you fearing that he'll be stabbed or poisoned, because of those limits. The core members can have a life because of those limits. There's risks of course, but you know that there isn't an assassins after you. if someone want to kill you, it will be fair play and you'll have a chance to be the one who will survive ; it will not be a stab in the back during your sleep.
The instant the word would spread that the Ombra tried to kill someone in the DeLuca main house, what become of those rules ? Who stay out of reach in such case ? They would become a threat for all the Families and wouldn't survive long. Nazazi's apology is nothing more than him saying that the rules stands and, therefore, him protecting his Family.
But this do not prevent the said Ombra to attack frontally the DeLuca main house. It would be fair play, too bad if they weren't able to see them coming.
then removed Mina's leading powers, i would highly doubt anyone would have the balls to not only support Mina but get into an all out war right after that,
Firstly, like I said above, since no one except a handful of members, know what happened, there's no "after that" ; especially since Nazazi is a crazy drunkard, what is surely well known in the Family.
But now think about it a bit more. Brizio had the balls to pull a gun on Nazazi. While not in command, he stay the Head of the Family, what mean that Brizio pulled a gun on the person he swore to serve and protect ! This seriously question his loyalty, that clearly goes to Mina, not to the Family. And this raise another question, how many in the Family share his views ?
He isn't the only one, we know it, thanks to Siobhan. Nazazi ordered men to follow and protect her (in the same way that Wilfred put gents on MC's back I guess). And what happened when Mina told them to not do it ? They were ordered by the Head of the Family to protect one of the heir of the Family. Then when ordered by the person in command to stop doing it, they didn't even cared to report to the Head ? Their loyalty do not goes to the Family, and anyone who's loyalty goes directly to Mina wouldn't care this much what the dunkard Nazazi say ; once again except the handful who know what happened and have been ordered to not talk about it.
specially when the daughter would be there as well (as she was going to Deluca's Estate).
We don't know how many time there's between the two events. Generally when they are directly linked in time Hopes group them on a single event.
Of course, they come in the same update, but this don't mean that players who starts with this release will not play a mission, or some side events, in between. Therefore expecting Siobhan to appear at the end of the scene seem wrong ; it's more surely an implicit event that already happened.
Anyway, if it happened the same day, then they wouldn't know what happened in the Family. Their mission would have started before it, and no one bring a cellphone with him when he plan to frontally attack the main house of one of the top five Families.
To this we need to add the problem of firepower, its not like Deluca's are a small family, that kill shot would require the enemies to invade the perimeter first, and they don't have much firepower, much less if its just one portion of the Ombra family.
No, they haven't invaded the perimeter. Invading it wouldn't have been unnoticed, there would be gunfire, and we would have seen Wilfred interrupt the dinner, letting some gents lead at least Cordia (who would have refused), Gracie (who would have been offended) and Isabel in security.
Even a peaceful direct infiltration wouldn't have been unnoticed. One totally unknown person don't walk straight to the main house, while carry a big bag, without it raising suspicion. And the more there's people doing it, the faster they'll be people stopping them in order to know what they want ; what would then lead to the gunfire I talked about above.
The only way to do this is a long time infiltration meticulously prepared. Therefore, rogue Ombra still are plausible responsible. Between the loyalty issue and the time needed to perform the operation, it stay a valid answer.
This said, I agree that it's not the sole possibility, just the more plausible in term of story and as long as we know, there's also the "someone" option. The same "someone" who poisoned MC, corrupted a DeLuca soldato to permit a direct attack against MC, and passed a contract with the Ombra for MC's assassination. Their own assassin failed, the proxy they used failed, and the assassin Family they payed terminated the contract. It's also a reasonable guess to think that they now goes more frontal.
But, while this wouldn't lead to a direct war, since it's an unknown player, it feel like a step too far and too fast. What doesn't mean that it's not what happened, I'm not Hopes' mind, just a player like all others, so I can be wrong.
