Just because dean's siren was a man that doens't mean that he is bi , the siren represent what he really wanted in a person in that precise moment and to dean what he needed most was a BROTHER who could understand him , he just got out of hell , he wanted all the support he could get from a BROTHER who seems to have change in the time he was away . That's why his siren was a man , a brother , not just because dean secretly wants to be with a man .
okay, sure, that’s your interpretation. but you do know that people can have a different opinion?
my interpretation of this episode was this: siren is a creature that disguises itself as someone that you would want to have a romantic relationship with and would be attracted to (have sex with). logically, i shouldn’t even say anything else. cause that’s just it.
dean even describes it as ‘whatever floats the guy’s boat’. one of the meaning of this phrase is whatever turns you on, interests you, suits you, something you like, your preference or choice. the siren itself says that all it wants is to fall in love over and over again.
there are two examples of how siren works in the episode, and all of them were romantically/sexually based. if spn wanted to make clear that all dean wanted was a platonic relationship with someone who understood him, it could’ve tried better.
so no, don’t act like my interpretation is less important and meaningful than yours. i have as much right to it as you do to yours.