I'm glad he stopped doing abortions. I am sad, however, that he converted to the Orthodox religion instead of the Catholic faith. You would think that seeing St. Thomas Aquinas would have given him a clue.

Not to commit blasphemy against Holy Spirit,but I believe that this vision is fruitless (therefore not from God).
what does it profit a man if he gains the whole worold but loses his soul?
what does it profit a man,if he saaves the lives of thousand unborn children,but goes to hell himself?
in my country,some people are reported to repent of their sins (eg.impurity)after seeing a moslem Imam in a dream.some people even claim to have seen Mary or Jesus,and they become better moslems after these visions.
devil can bring a fake conversion.
good actions done in the state of mortal sin (schism)are purely natural and devoid of merit.

If it was realy Saint Thomas he will make him CATHOLIC

People can still refuse to cooperate with grace and with the obvious signs given to them. How many saw the miracles of Jesus yet still refused to believe He was the Messiah? I believe that St. Thomas Aquinas probably did appear to him. Just has presence was a sign of the truth of the Catholic faith but the doctor did not see the obvious. God often times does not come directly at you. He gives you clues and leads you through hidden means - it is up to you to see the obvious signs and message God is trying to give to you for your conversion to the Faith.

Give him a chance, he may yet become a Catholic.

Yes, and let's be delighted that he converted from a life of sin to a pro-life position, even if he is unfortunate in that he has converted to the Orthodox. It wouldn't be the first time that people have had half-way conversions and come to the Church soon afterwards.