Why won't Capulet let Tybalt deal with Romeo? What does this say about Capulet?

Capulet wants his party to happen free of strife or ugly brawl. He says he knows Romeo is a respectable boy even though he is a Montague. Capulet is asserting his authority with Tybalt and Tybalt is forced to back down. Capulet is "the king of his castle" and Tybalt is a mere boy.