The autor likes muscular girls and lolis AND draws in moe style... If this were hentai it would be really weird
Maybe the author can do more than one art style. The art seems like it's done to strengthen the impact of the content--note that the MC is obsessed with moe stuff (dressing little girls in frilly dresses and such); with both the character being moe-obsessed and the art being that style, it makes the "air force sergeant" reveal and the abs all the more unexpected, jarring and funny. Well played I say.