It's a dark comedy. I'll get you the definition of it.

Black comedy or dark comedy is a comic style that makes light of subjects that are generally considered serious or taboo.

AKA a human who develops zombie like tendencies and needs to eat other humans in order to live, the only problem is she is fully aware of it and her husband knows about her situation so what happens? They have to find a way to keep her alive but through "legal" means. The taboo is the fact that yes it's cannibalism in the sense that she is still a talking person but she is technically zombified, but see going by this logic you would have to say every zombie movie supports cannibalism because because it's human eating other humans.

First understand what it means to make a Dark Comedy before assuming the worse of it, and man, Mrs. Doubtfire? You seriously think Robin Williams dressed up like a woman in an attempt to later normalize transgender issues? You ever here the term androgynous or cross-dressers? Sorry to disappoint but people been having sex identity issues for a long time it's just now that it's reaching the light of society now because the media feels they can exploit it for their own personal gains along with politicians.

Back to Mrs. Doubtfire though, Robin Williams' character was an unwilling cross-dresser in this situation, it was never about his wanting to be a woman, it was about him doing anything to be with his kids because the Mother wouldn't allow him to be with them because of his lack of a job. The humor comes from how he holds a job, to watch his kids but he can't outright admit it's him because of how he's dressed. But he did what he did because he loved his kids and wanted a way of being with them without losing them. It's more about the flaws of a justice system that would side with the mother rather than the man in many situation because she's the one that gave birth to the children even though pregnancy takes 2 to happen.