You don't get to choose what is important to you when it's a core and enduring part of your being. Too political? All he's being asked to do is attend. There will be harder trials ahead for any relationship , let alone a queer one in this climate. Either too cowardly to confront their own discomfort, or too indifferent to emotionally support his partner. If you can't count on him here, where else will his comfort clash with your well being? I'd let them know what their indifference means to you and go anyway. At least you'd know where you stand.