He vastly overestimated Tom's ability to calm Sonny down. In all fairness,Tom did advise Sonny that "if your father dies,you make the deal" as well as telling Sonny 'I think we should listen to what he has to say" referring to the meeting that Sol wanted to set up, but as we know,he was wasting his breath.
Very good point.
As Capri posted Tom did calm Sonny down
I reckon Sollozzo estimating Tom's ability to calm Sonny down was the only one correctly surmised, out of all the over and under estimating
No doubt all their tactics was just a ploy buying time
They were never going to or needed to negotiate anything with Sonny Every tactic was stalling for time
The key was killing Pop Vito's politicians would go over to the highest bidder as more than anything it was always the money
