Age of consent in Texas is 17, nothing illegal happened . He thought the better of it and didn’t follow through; the girl was not forced to do anything. Lived an exemplary life since. Perhaps he shouldn’t have continued in the ministry...instead, just got a regular job, got married and lived an exemplary life.
Sounds like another Genesis 39 hit job to me!
I don't agree with the catholic interpretation of the Onan story anyway (although I am pro-Catholic: I just don't think they get every detail correct).