"My dad believed in you, I am not gonna make the same mistake" is less about belief and more about how Rooster here is rejecting Maverick's love. Rejection of Maverick in the Bradshaw family.
Otherwise, I don't think Rooster would've reacted so strongly to Hangman trying to imply it was Maverick's fault his dad died. Or he would've told Phoenix about it. Like the two are friends, I don't think he would've hidden his feeling from her.
It was just about hurting Maverick because Rooster had years of bottled up rage. And he tried to give back all the pain he had been feeling.
Maverick however converts it back into love, and that's what makes this movie so great.















