Firstly, Sam isn't ashamed of being gay. He would've pulled a Colton Haynes if he did (Gay photo's on the net, pretends it didn't happen). He just has a professional image, and a personal one. We still see him act like he used to, just not when he's working.
Secondly, Sam never says "She" or "He" in his songs, but we know he's singing about a Man. But so he can relate to everyone he keeps it Neutral. He also never pretends to be straight in his video's. His latest video features a straight couple, but he is just telling the story.
But it's called Gay Stereotyping that a Gay person must relate everything to being Gay. It's what setting back the Gay community several years.
I'm pretty sure Gays are trying to shake off the fact that to be Gay everything must be "feminine" and "Gay". Being Gay is just a sexual preference. It doesn't always have to come with the whole package.
Sam has has no shame telling people he is Gay, therefore he's not ashamed. He doesn't have to bring the stereotype to his music or to his professional image. He likes Men. That doesn't mean everything has to be about Men.
I'm pretty sure Gay's hate when a straight person acts homophobic because they think you sexualise every male because of the Stereotype that Gay's are in. And now you are getting angry that Sam is breaking that Stereotype. Like Really?