Calling it a “political litmus test” is a way of belittling choices that all people make. For example, I really dislike bigots, so I’m not friends with any. I’ve worked with bigots and been in the same public space as bigots, but I don’t have to be friends with them if I don’t want.
Belittling people for having standards and making choices is a strange, solipsistic thing to do. Also, it’s most likely hypocritical as I’m sure there are some kinds of people you are not interested in being friends with. Maybe your response is just defensive because you like the kinds of people the author doesn’t like and don’t like the implicit criticism of yourself.