Thats one of the main reasons he picked up Tom. Sollozzo knew that Sonny would search high and low looking for him,sending all of his men out on the streets.Sure he would have to lay low for a while, but Tom would soon see that the war was costing them a lot of money. Tom would have to stop Sonny, being as thats his job, and by Sollozzo catching Tom, he could prove to him that agreeing was the smart move. Hell everyone knew that already.Sollozzo hoped that Tom would calm Sonny down much quicker and get him to agree faster.