This is less of a Bad History Take and more of a Bad Linear Time Take. They "get their foot in the door" by being in power?
I think the Bad History Take in these type of views is less the idea that the Nazis targeted trans people first but that Nazis "snuck" into power and then went full-on card-carrying Nazi like five years later or something and everyone in Germany was all "oh shit, did not see this coming" and felt like they had screwed up but now there was nothing they could do. It combines a lot of myths that deliberately ignorant people like Kevin all believe to be true, that the Nazis hid their views and goals to get support, that they were elected into power and supported by most voters, that the Weimar Republic was like America and then suddenly over night was authoritarian, that everybody and elsewhere loved Hitler and thought he was the best thing ever, etc.