I will argue with my RC brothers and sisters over all kinds of things if I think they're wrong, but it's not helpful to ascribe this to them until some of the more knowledgable RCs sign onto it.
My guts tell me that spunkets is entirely wrong on this and is grossly misrepresenting Catholic teaching.
That's correct.
"Nevermind that the Bible refers to Him as the creator."
Creation included the incarnation. Before God decided to create, He was not a trinity. The eternal person of the Trinity is the Holy Spirit and the being of the Father that held that Spirit. It is the same Spirit that was incarnated.
"Nevermind that when earth was created, God said "Let US make...""
God is talking to Himself here, just as He did in the Gospels often. The human being that held the function and responsibility for God's Spirit in this world was Jesus. It is the same with a man and His soul that provides for the function of eternal spirit.
The man, from his own free will determines the character and makeup of his spirit and thus the destiny of his soul. Man is in the image and likeness of God. He is also a trinity. The man is the right hand man of his soul.