Trump isn’t a social conservative.
Exactly. Trump's actual policy positions generally trend toward the mainstream of public opinion when it comes to social issues. He's not pandering though, he seems perfectly sincere with this. (Polling has consistently shown for the past several years that ~60 percent of US adults are in favor of same-sex marraiges). We don't have to like it, but pretending it isn't so isn't productive, either. Same goes with second amendment issues. Trump was quick to want to ban bump stocks, for example.
Watching the Trump haters, they focus almost entirely on his affect, not his policies. Policy wise, at least on the social issues, he's a moderate. Every politician is a mixed bag, and Trump's no different, but where he is different is with his candor. Of course he must know that his most fervent supporters take a dim view of the blasphemy that is "gay marraige". Trump must know that this won't help him at all with the homosexual voters, and that it must hurt him at least somewhat with his base, but he has the strength of character to go with his own personal beliefs on these issues. People respect that, even when they think he's wrong on the merits. After all, who wants the Vicar of Bray at the helm in times like these?
It is easier to say he's the lesser of several evils; that until something better comes along that has a chance of success vote for him.