It’s not helpful to pretend someone’s comments are run of the mill homophobia or transphobia when they actually brought up legitimate and important issues (not the drill instructor thing).chances are your DI encountered a person or two who was gay, or maybe even liked to wear dresses. Whether the DI knew this, or not, is unclear.
As for the rest of it, well change is never easy and there are always some who resist. There was a time when captain kirk kissing lieutenant uhura was considered borderline scandalous to the point where NBC executives, worried about the response, ordered two versions of the scene be shot. One with and one without a kiss.
Now days we wouldn't even bat an eye, though i do know a mixed race family here in town who have had a good ol' boy or two try to lecture them about the mixing of the races, so maybe things are moving fast enough.
Don’t you see a difference between a white man kissing a black woman and someone being supported and encouraged when she says she is a man even though objectively she is not?