"WHen I did Aquinas on the Sacrament I seem to recall that he acknowledged the validity of Orthodox orders."
Could be; I've never heard that.
"Or maybe Aquinas wasn't representative?"
That's certainly possible. Aquinas wasn't representative of a lot of what the Latin Church believed both before and after his death, the Immaculate Conception for example.
I think you will find that for many centuries, Rome looked at the Orthodox as being wholly outside the Church because our bishops were not in communion with the pope and would not submit to his claimed universal immediate jurisdiction.
Article 4, Q 74, Tertia ParsThe question is whether it is mo' better to use leavened or unleavened bread. Much to everyone's surprise He comes down on the side of unleavened bread, but in the course of his discussion he says it would be a sin for Greek Priests to use unleavened because she should play by the rules of their team. (Dawg paraphrase)
I always understood this to mean that he thought there really were Greek Priests.
To tell the truth, all I remembered was the question was in the 70's, AND the opinion about playing team ball.