Anything that can be expressed as even a single digit percentage is electorally significant in elections where things are often, as you pointed out, determined by mere hundreds of votes. So the LGB part of the equation is significant.
Yeah, except the construction was that he "can't win without them". You literally can't win without women, they're 51% of the general population; fair enough. But you
can win without black votes; Republicans have been doing that for decades, getting only 5% there, and sometimes with enough margin to win with 0%.
And you
absolutely can win without that 2% gay vote. Obama's margins were comfortably above 2%, and xenophobic homophobic teh Hitlerz Trump won, presumably without any gay person voting for him (even though he walked across a stage waving a rainbow flag).
It's the state level fights that hinge on a sliver where you need every vote you can get. Those fights matter because the small margin tips a chunk of electoral votes into one column or the other, which is when that tiny demographic may be important... but wait a minute, who's the party that's all hot and bothered to kill the Electoral College? Can you say
gay erasure, you popular vote-fetishizing
bigots?!?
What isn't is troons. They're a rounding error.
They're several other kinds of errors as well.
I'm waiting for the year that polling doesn't just ask Democrat/Republican, race, etc; they start asking about gender and sexual orientation. We know where all the non-cis responses will wind up, but it will be funny to prove the groupthink. I don't think the special snowflakes, so desperate to make up terms and fashion to flaunt their uniqueness, appreciate how easily you can be dismissed when you become predictable.
"It's not sir, it's MA'AM! Wait, don't you want to know who I voted for? What do you mean you already know?"
Plus we'll see normies get mad when a pollster on the street asks about their gender. Some fool with a clipboard is gonna get slapped...