Why does Heck Tate want to cover up the real cause of Ewell's death?How does Atticus misinterpret this?

Heck Tate wants to protect Boo Radley. He knows the limelight of having saved the children would hurt Boo more than help him. Boo is very much a fragile Mockingbird who would not survive old ladies bringing him cookies and newspaper reporters at his door. Heck Tate knows there is a time for altering the truth. Atticus is more decided. His morality and lawyer's ethic dictates telling the truth. In this case, however, he understands that reality can be a messy thing and sometimes the truth does more harm than good.