You probably won’t find a magic bullet solution to such a complex subject here. Use your best judgement, tempered with wisdom and humility, and above all... count your blessings he didn’t come back from college with a methamphetamine addiction. That’s when you throw in the towel.
My sister in law and my older sister are both liberal and both quirky, they both start yelling rather than discuss and they both have been kicked out of my house. They both have made a lifetime of stupid decisions and their children are all just as stupid as they are.
But the rest of my 150 some odd relatives are normal Americans. Go figure.