Not even Saburo arasaka has those rights but he is rich and powerful enough to simply ignore it.
Nah. Game is actually very clear about this.
While there's spoiler that in title, still heavy spoilers ahead for one of the endings.
If V chooses to become an engram, it's stated that he is essentially property. However we also learn that his body died, he was stored temporarily so Arasaka scientist could create new body for him. V is in this new body when V is described that engrams aren't citizens, yet V is a citizen.
There is also something else.
I was thinking about other possibility, but then if you don't have any rights as human, you can't own anything, money, stocks, property, can't even sign anything. Scenario where Saburo would have power only through Hanako isn't plausible as he still couldn't make any sort of statements (like what we hear) or agreements behalf of corporation without procuration rights. Killing him or any human restored from engram wouldn't be a murder if restored engrams wouldn't considered to be human.