While an ice cream made from “gay” people would not necessarily violate the meat-milk rule, it would definitely be non-kosher, and might also violate “ever min ha-hai” (dependeing on whether the person was schedchted before be added to the ice cream). There is also a risk of various diseases. Note that halacha prohibits canibalism in all cases. I suspect the taste would be an abominable.
Seriously, kosher food companies should avoid politics. The fact the people on the “blue side of the spectrum will pay for a hecksher is a good thing. Indeed, many of the non-Jewish firms who produce kosher foods have left-wing views. If kosher certification were limited only to companies that market exclusively to frum Jews , the choice of products would be much less, and the price much higher (as is the case with companies that in fact limit sales to the frum community).