So this is the legend I've heard so much about in the few days of being a member?

I think you hit the nail on the head. Michael's goal in all three films is to protect his Family and his family. It should not come as a secret that he would leave the Lake Tahoe compound, hence protecting his civilian family from harm. I never questioned it.

What's more, he played Roth exactly the way he had to. By visiting him and telling him that he was unsure of who was behind the attack, he bought himself more time to figure out exaclty who in his Family had fingered him for Roth. Remember, Mike didn't want to kill everyone, only his enemies. One of these enemies was still hidden to him (Fredo, you broke my heart), so he had to buy time in order to get him. He could have killed Roth on his birthday right after he announced that Roth's estate would go to Michael, but he just had to find out who the rat was.