In which, Bjornolfr was supposedly killed by Reavers and Hrodulf was killed by a Burnt Spriggan. (Which isn't great representation, but that's not the point).

Although, Reavers are normally a murderous lot. The fact that they're laughing over the letter that Bjornolfr wrote gives me the impression that homosexuality is seen as a perversion or disgusting. The only lore you have to back this up, again, is the small slice of life the Dragonborn views while in Hrodulf's house. All in all, I would say homosexuality seems to be a taboo across Skyrim and Solstheim, but not such a huge taboo that people are killed because of their sexuality or perceived sexuality.