That’s what machiavellian distills into - cold pragmatism and disregard of morality. So his turn from okay guy that wanted his family to stop with illegal shit into someone much worse than his father was portrays it perfectly.
Unscrupulous is only one of the definitions.
Cunning and scheming are the other two. The Prince detailed how to gain and hold power.
It wasn’t a book that said immediately shoot everyone to solve all your problems.
So the original author was expecting violence in Godfather 2 but with more planning.
You gain and hold power by killing people you don’t like, look at any dictator that ever dictatored. 🙃
Also, knowing who to shoot and when to kill them is kind of a big deal.
The man who shot Don Vito thought he was untouchable because he was going to the meeting with a police captain.
'CAUSE IT HAS A VALID POINT TO MAKE, IT’S INSISTED!
The Machiavellian part was the fact he removed his rivals simultaneously without them gaining prior warning.
He was cunning like a fox to avoid detection and dangerous like a lion when action was required.
Historically speaking, it tends to work.
And for the record, Machiavelli didn’t exactly rule it out.