Watterson specifically made Uncle Max to explore the possibilities of extended family and then realized that it wasn’t going to work, since the parents don’t have names and so much of the action takes place in Calvin’s head. As such, Max was of course unencumbered and mysterious, we don’t need Aunt Lacey and the damn kids, too.
But, that lack of a heteronormative nuclear family, bits like Calvin asking if he hasn’t met Max because Max was in jail and his Dad admitting that that’s not actually totally unlikely, and genuinely poignant shit like “sometimes I think all my friends have been imaginary,” really do make him seem gay. Especially when you add the time the strips were published to that shirt, the lean, that FUCKING mustache(!) and the proud tradition of gay uncles everywhere.
