Could be he has a rainbow family member.
I know a family who had an intelligent, curious, open-minded daughter. She went to an Ivy League college, and while she was there became almost unrecognizably leftist. Strident, arrogant, extreme. Didn’t want to hear a single word that contradicted her new world view.
While she was at college, I noticed their family car (a minivan) had an anti-petroleum-industry sticker on the back. “No blood for oil,” or something like that.
Once she graduated and moved out, someone tore that sticker off the back of the car. I’m pretty sure the tearer was her father, though I’ve not asked him.
Sometimes you let your kids do things to keep the peace. It matters more to have a peaceful home than it does to argue some political point that you know the kid will probably eventually see the light on anyway.
Indeed it is hard to deal with personal issues along with political. Happens to me frequently.
However, even if I had a homo loved one, I would not put out a flag nor a bumper sticker for him. Even just for June (extra grating because it’s my birth month and my father and sister, though they RIP).