He knew EXACTLY how Sonny, as the Don's son...would react, which was why he bothered to kidnap and speak to Tom. It was also why he took the time to kill Luca as well...whom he knew unlike Santino could NOT be reasoned with.
SOLLOZZO : Your boss is dead. I know you're not in the muscle-end of the family, Tom, so I don't want you to be scared. I want you to help the Corleone's, and I want you to help me.
Yeah, we got him outside his office just about an hour after we picked you up.
So now it's up to you to make the peace between me and Sonny.
Sonny was hot for my deal, wasn't he? And you knew it was the right thing to do.
TOM: Sonny'll come after you with everything he's got.
SOLLOZZO: That'll be his first reaction, sure. That's why you gotta talk some sense into him. The Tattaglia family is behind me with all their people. The other New York Families will go along with anything that will prevent a full-scale war. Let's face it, Tom, and all due respect,
the Don, rest in peace, was slippin'. Ten years ago could I have gotten to him?
Well, now he's dead. He's dead, Tom, and nothing can bring him back. So you gotta talk to Sonny, you gotta talk to the caporegimes, that Tessio and that Fat Clemenza.
It's good business, Tom.
TOM: I'll try, but even Sonny won't be able to call off Luca Brasi.
SOLLOZZO: Yeah, well, let me worry about Luca. You just talk to Sonny -- and the other two kids.
TOM: I'll to my best.
SOLLOZZO: Good. Now, you can go.
I don't like violence, Tom. I'm a business man. Blood is a big expense.
[THEN, ONCE TOLD THAT VITO HAD SURVIVED THE SHOOTING, SOLLOZZO CONTINUES TO INSIST TOM TO TALK SONNY INTO MAKING A DEAL]
SOLLOZZO: He's still alive. They hit'em with five shots, and he's still alive! Well that's bad luck for me, and bad luck for you if you don't make that deal!
*****
Apple