Lame indeed, but twist endings meant to frighten and titillate are formulaic Hollywood fare, seen as a good way to ring the cash register. Plenty of writers are less interested, sadly, in making good art than in figuring out how appeal to as many people as possible. This is understandable (a boy’s gotta eat) on some levels, but it’s disappointing and, as in this case, stereotyping.

Once upon a time, stock Hollywood psychopaths meant to frighten people for pleasure were gay folks and trans people. Storytellers want bogeymonsters in their stories, because they’re effective. Nothing necessarily wrong with that, but when writers resort to stereotype, they are being, as you say, lazy. And harmful.