I agree with you. I know rumors were going around before about his sexuality, but if they have confirmation, that angle could have something to do with his disappearance. Or did he fake his disappearance so he could go live out that life style?
Also, I do wonder if his dad could have had something to do with his disappearance. They straight out said his dad would never approve of his son being gay. They also said his dad drank a lot and was cheating on his wife while she was going through cancer, which maybe is other reason why Brian didn't care for his dad.
Also mentioned that someone sent in a tip that Brian's brother was responsible for his disappearance.
So many different angles