Sollozzo wants what he wants and will do anything to get it.. even though vito wasnt going to be a brick wall stopping him in his tracks, he didnt want a speed bump down the road either... Sollozzo's drugs would have made it to the corleon's turf. a war would have begun and by than Sollozzo may have been too strong to stop. he just thought by sunny making his comments that he had the best chance while it was still fresh in sunny's mind