Honestly, I think that rule is intended more to fend off wank about Reylo. The hate for that pairing is already incredibly OTT (villain/hero is not new, even incest - I'm guessing none of these people wank so hard over Thor/Loki) so something needs to be put in place to acknowledge both the people who ship Reylo and the people who don't. Even with rules stating that abuse is allowed as long as it isn't romanticized they still instantly got a "Reylo is abusive by default so it should be banned" comment. It doesn't mean hate sex and non-con aren't allowed, just that "non-con that immediately leads to a happy ending" isn't allowed. I agree the rule isn't ideal (it should be something more to do with mandatory warnings, rather than an outright ban) but I also get why the mod felt they had to put something like that in place to deal with potential pairing wank.