I notice the site above (my second link) says
3b) WHY 5-POINTED STARS?
Though The Life Guards flag stars had 6 points (as true heraldic stars should); on the Rhode Island "Hope" troops� flag the �stars� were 5-pointed � perhaps indicating its military use. Washington's �stars� must have originally meant spur-rowels because at the time the family were granted arms, stars (called estoilles) were depicted with six wavy arms (one of the many symbols of Christianity) whereas rowels (usually called mullets) were 5-pointed and pierced (a symbol of knighthood), though these distinctions were later forgotten.