He should have written Planned Butcherhood on the the shirt
I agree there was fertile ground for something more.
Perhaps that’s the genius of it, him having the viewer fill in the blank themselves.
There is a tactic in presentation, that incorporates leading people to your conclusion, with them thinking they thought of it first.
Have you noticed how some movies will present scenes that let you in on something the characters don’t pick up on? You sit there feeling pretty smart for having figured it out, and cranky because the main characters aren’t already acting on what you know.
This may be something akin to that.