I have someone in my life who uses threats of suicide as her manipulation tactic - not for sex, but just for things she wants. It's pretty exhausting to be honest. With her it's more like, "I want this thing to happen" & you'll tell her it can't happen & she'll tell everyone she's going to kill herself. So it seems while this person uses that empty threat to manipulate people into doing what she wants, this guy seems to use it to steer things into sexual situations. That's been the pattern so far, it seems, anyway.
It's seriously messed up, & I really don't know what makes people go to that extreme. Just be careful & pay attention to what people say in those scenarios. There are some truly sick people out there.