Most people coming out against SSM or gays in general because of `trans issues have just been waiting for an excuse to voice or re-voice their bigotry as it has been very unacceptable to just be bigoted for no reason. But now they can just cite a tik tok concerning a facebook post about a kid identifying as a cat and using a litter box in school and how that means "they" are trying to force LGBTQ ideology down everyones throats.
In some cases, but I think a good number of people really do have a different reaction to "gay and lesbian" than to "LGBT."
Take Musk as an example, a day or two ago a gay person on Twitter asked him if he was cool with the gays specifically and his response was basically "yes, I think people are born that way, just try to still have kids." But then a few hours later he shared a scaremongering post about "LGBTQ+" ideology in schools. A lot of conservatives view gay and lesbian as fine but LGBT as problematic, as the latter is associated in their mind with an ideology and the former with an unchanging biological trait. I'm not saying this makes it right, but I think it's more complicated than "they've always hated us and always will."