There are child molesters and homosexuals who are also married to women. Some cover their sexual crimes through the disguise of being married. It's not a matter of achieving orgasm that a homosexual or molester attacks human prey. Rather, it's the sinful vice of lust. This sin is no different in disobedience than rage, gluttony, sloth, vanity, envy, or greed.
Thus, a married man (or priest) who engages in lust has no protection from lust by merely being married. That man has lost his will to sin and it's the sin that binds him from being chaste in celibacy.
Furthermore, the mission of Holy Orders is so demanding a life that it takes an entire life's commitment to fulfill the daily vows of priesthood for men and being a nun for women. But I'm sure you know Catholic response to Holy Orders.
Really? Then why has the Vatican allowed over 400 converts from Anglicanism and Lutheranism, 98% of them married with children, be ordained?
Lust for power over a more vulnerable person, usually.