Will had instinctively known that moving up the trip was the right thing to do. If he hadn't, there was a good chance Roberto would have found him.
What exactly did he think he would accomplish by doing this? Will was never going back to that life. He had clawed his way out of the dark and would not let anyone drag him back no matter what he had to do to prevent it.
There was only one reason Roberto would want to know his boss's true identity. Blackmail.
This could happen one of two ways. He could threaten to expose the illegal activities Will's squeaky-clean alias had been up to or he could somehow use Hazel. If he knew who William Sheffield was, he had to know about his wife.
The latter was more likely based on Carlos's intel. Roberto wanted him to come back and run the ring; that wouldn't work if he was in jail.