And obviously if Jesus as God did not remain a virgin the He would be breaking His own laws,yet if He married the history of the world would be strikingly different.
Fr. Reginald Garrigou‑Lagrange, O.P. discusses the office of mediator:
"The office of mediator belongs fully only to Jesus, the Man‑God, Who alone could reconcile us with God by offering Him, on behalf of men, the infinite sacrifice of the Cross, which is perpetuated in Holy Mass. He alone, as Head of mankind, could merit for us in justice the grace of salvation and apply it to those who do not reject His saving action. It is as man that He is mediator, but as a Man in Whom humanity is united hypostatically to the Word and endowed with the fullness of grace, the grace of Headship, which overflows on men. As St. Paul puts it: 'For there is one God, and one mediator of God and men, the man Christ Jesus: Who gave Himself for a redemption for all, a testimony in due times' (I Tim. ii, 56). "But, St. Thomas adds: 'there is no reason why there should not be, after Christ, other secondary mediators between God and men, who co‑operate in uniting them in a ministerial and dispositive manner. Such mediators dispose men for the action of the principal Mediator, or transmit it, but always in dependence on His merits. [1]
Actually there is a reason, God made no provision for other mediators His word. In Fact He clearly excludes another
1 Tim2:5 For there is one God, and one mediator of God and men, the man Christ Jesus: 6 Who gave himself a redemption for all, a testimony in due times
"St Thomas'" words were not added to the infallible scriptures they are his own personal opinion and nothing more