Early intervention for dyslexia is vital for children who attend traditional school. However, children who learn at home do not face the narrow learning constraints imposed by traditional classrooms. In a classroom, most learning occurs through books, so reading at an early age is essential. Parents who teach their kids at home can and do utilize many other methods (reading aloud, audio and videotapes, hands-on experiences, discussions, etc.) As a result, many parents of children who exhibit symptoms that may indicate a learning difference, choose to wait it out. Like your husband, many kids simply mature and outgrow the problem.
Several moms in my homeschool group reported that their kids exhibited word reversal until they were around ten-years-old. Most gently corrected their children. How long you wait is your decision, based on your son's behavior and learning abilities. For more information about dyslexia, read When Reading Is Rough.