Well Mon- Fredo at the superman show was a way of showing that fredo was a weak, perverse, womanizing character. How could FFC and Puzo have known some guy years later was going to make Freddie bi and some folks would look at this scene the wrong way. As for the other stuff...
...about Paulie-that is as homophobic an explanation as I have read.
...about Vito- Freddie was weak, but he always felt he had to prove himself to his father, given who his brothers were. There is nothing homosexual about that. especially given the times and ethnicity of the stroy, it was very common for sons to need thier father's approval.