Conservatives are obsessed with social conformity and rule-following. They hate change, difference, and those who don't 'fit in'. Trans people don't fit into the neat binary of male/female and don't follow strict gender roles. So by definition they are evil/bad/wrong/corrupting and a 'symbol of social decay' or whatever.

Conservatives see the existence of trans people as violation of the social order/contract or as unnatural. They see them being endorsed by the govt as fully fledged human beings as an offense to their beliefs and a threat to to their way of life. So they lean into this outrage narrative by pushing/magnifying any story they can that trans people and their supporters as 'brainwashing' children and they pull out the who 'groomer' thing because they see pedophilia as the ULTIMATE EVIL that anyone who is disagrees with them must be guilty of, because disagreeing with them is evil in their minds.

The rest is just the false narrative they construct to further solidify their views that trans people and trans supporters are evil. So they go on about children being forced to change sex and being 'multilated' by sex changes ops. None of which actually happens, but you can't let the boring facts of reality get in the way of your narrative about how trans people and trans supporters (and the big bag government!) are raping and physically mutilating the poor innocent children who need to be rescued by the brave strong heroic conservative who will restore the natural order and throw all these evil child abusers in jail!