Yeah, that’s the difference between eisegesis and exegesis; too many people read into Scriptures their preconceptions then they say ‘see, I told you, that’s what it says!’
It’s like those reading that Jesus wrote down the names and/or sins of those who were accusing the woman of adultery or Saul falling to the ground from “a horse;” there’s no evidence, but they believe it wholeheartedly… ‘so it must be what God intended to Reveal.’
If he wanted to scam the father, why would he insist on the course he determined to follow?:
15:21 Then his son said, “Father, I have sinned against heaven and against you. I no longer deserve to be called your son.” (St. Luke)
On the previous verse the father had already ran to him with love and affection in his heart:
15:20 So he left the place and went back to his father. ‘While he was still a long way off, his father saw him and was moved with pity. He ran to the boy, clasped him in his arms and kissed him tenderly. (St. Luke)
Most of the people I have known deflect any semblance of guilt the second they believe that they are past any reason to own up to their responsibilities and obligations.
The words chosen by the son are very exact, Calling God as witness: ‘I have sinned against Heaven…’
But, we are free to form any opinion we choose; that’s that “freewill” thing.