The final cut of the movie didn't convey this well, but the intended implication of "Riddick" is not that Katie Sackoff's character was converted into being straight by Riddick, but that she was pretending to be a lesbian and he saw through her.
I've read somewhere that in original script there was a scene where Riddick told her that he knew she's not lesbian because she had her nails painted pink. But nevertheless someone decided to cut it out and didn't find problem in leaving it this way - that a lesbian (since there wasn't any reason anymore to think otherwise) has been turned by right guy.
FInal product matters, not intentions of particular person, especially since there are always many people involved in creation of movies and TV shows. An example of NBC Dracula shows it perfectly. It's one of many shows that introduced "lesbian sleeping with a man" trope, though the creator and writers wanted it to look like she was traumatized by the experience. During execution, someone decided to make it look like the lesbian enjoyed sex with a man greatly, which also made that particular storyline completely nonsensical in the context of what happened before (for example, the lesbian showed revulsion before when she was forcing herself to seduce the man - though it further implies "turning").
So it seems that this kind of portrayal is actively pushed by TPTB of the media. Here's Dracula's creator, Cole Haddon, tweet about Dracula's incident (obviously some spoilers revealing for example which character has been made a lesbian in that adaptation, and who she slept with):
https://twitter.com/...506045349015553