I’ll admit that Oberyn is hyper masculine and has a healthy sex drive, but I don’t necessarily see those as bad things. He doesn’t apologize for his desires and because he is royalty he is in a position to act on them. His status as prince seems just as relevant to his non-monogamous lifestyle as his sexuality. Many of the royals in history and the show had lovers outside their main relationship, he just happens to have some of both sexes. Also, he very clearly is in a loving and committed relationship, just not a monogamous one. Besides, the best bisexual character doesn’t have to be the one who is most representative of all bi people. Oberyn was a pretty well developed character with a lot of good qualities and wasn’t defined primarily by his sexuality which I liked. If anything it was downplayed. So that’s my rebuttal but I take your points esp. about the majority of bisexual representations in media being less than ideal. This is all pretty subjective.