I just had another comment on this, hopeful people will understand it.

My first reaction to this post was "NO, not acceptable at all." But I think some of that was related to my own experience.

Maybe Dad thought is OK to get arroused by his child as long as he retreats to the bathroom to finish himself off. IDK the men throughout in my life seem to have a different standard.

As a mother, the boundary is very clear to me. But as someone who has had my child boundaries blurred, I can maybe appreciate the guy's boundary confusion depending on his own upbringing.