It's a matter of narrative. He may not look like a zombie, but he's infected, he just haven't fully turned into a zombie yet, but he's still dangerous.
If you really want to, you can disable it by either removing or commenting out its line in entitygroups.xml, but I would advise to avoid that method, and instead create your custom patch that will apply after this mod, because every update to the said mod will overwrite your changes that you've made manually...